Hybrid automatic repeat request feedback in radio systems

ABSTRACT

A wireless device receives a sidelink control information (SCI) that may schedule a transport block and may also indicate a first repetition value. The wireless device may also receive a transport block via a physical sidelink shared channel (PSSCH). Based on a comparison of the first repetition value received via the SCI and a repetition threshold, the wireless device may determine to transmit an acknowledgment for the received transport block. The wireless device may then transmit the acknowledgment for the received transport block.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Pat. Appln. No. 16/927,366,filed Jul. 13, 2020, which claims the benefit of U.S. Provisional Appln.No. 62/875,588, filed Jul. 18, 2019, all of which are herebyincorporated by reference in its entireties.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of several of the various embodiments of the present disclosureare described herein with reference to the drawings.

FIG. 1A and FIG. 1B illustrate example mobile communication networks inwhich embodiments of the present disclosure may be implemented.

FIG. 2A and FIG. 2B respectively illustrate a New Radio (NR) user planeand control plane protocol stack.

FIG. 3 illustrates an example of services provided between protocollayers of the NR user plane protocol stack of FIG. 2A.

FIG. 4A illustrates an example downlink data flow through the NR userplane protocol stack of FIG. 2A.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU.

FIG. 5A and FIG. 5B respectively illustrate a mapping between logicalchannels, transport channels, and physical channels for the downlink anduplink.

FIG. 6 is an example diagram showing RRC state transitions of a UE.

FIG. 7 illustrates an example configuration of an NR frame into whichOFDM symbols are grouped.

FIG. 8 illustrates an example configuration of a slot in the time andfrequency domain for an NR carrier.

FIG. 9 illustrates an example of bandwidth adaptation using threeconfigured BWPs for an NR carrier.

FIG. 10A illustrates three carrier aggregation configurations with twocomponent carriers.

FIG. 10B illustrates an example of how aggregated cells may beconfigured into one or more PUCCH groups.

FIG. 11A illustrates an example of an SS/PBCH block structure andlocation.

FIG. 11B illustrates an example of CSI-RSs that are mapped in the timeand frequency domains.

FIG. 12A and FIG. 12B respectively illustrate examples of three downlinkand uplink beam management procedures.

FIG. 13A, FIG. 13B, and FIG. 13C respectively illustrate a four-stepcontention-based random access procedure, a two-step contention-freerandom access procedure, and another two-step random access procedure.

FIG. 14A illustrates an example of CORESET configurations for abandwidth part.

FIG. 14B illustrates an example of a CCE-to-REG mapping for DCItransmission on a CORESET and PDCCH processing.

FIG. 15 illustrates an example of a wireless device in communicationwith a base station.

FIG. 16A, FIG. 16B, FIG. 16C, and FIG. 16D illustrate example structuresfor uplink and downlink transmission.

FIG. 17 illustrates groupcast transmission of vehicle to vehicle (V2V)communications as per an aspect of an example embodiment of the presentdisclosure.

FIG. 18 illustrates groupcast transmission of V2V communications as peran aspect of an example embodiment of the present disclosure.

FIG. 19 illustrates groupcast (or unicast) transmission with repetitiontransmissions of V2V communication as per an aspect of an exampleembodiment of the present disclosure.

FIG. 20 illustrates a procedure of groupcast (or unicast) transmissionwith repetition transmissions of V2V communication as per an aspect ofan example embodiment of the present disclosure.

FIG. 21 is a flow diagram of groupcast (or unicast) transmission withrepetition transmissions of V2V communication as per an aspect of anexample embodiment of the present disclosure.

FIG. 22 illustrates groupcast (or unicast) transmission with repetitiontransmissions of V2V communication as per an aspect of an exampleembodiment of the present disclosure.

FIG. 23 illustrates a MAC CE structure as per an aspect of an exampleembodiment of the present disclosure.

FIG. 24 illustrates a procedure of groupcast (or unicast) transmissionwith repetition transmissions of V2V communication as per an aspect ofan example embodiment of the present disclosure.

FIG. 25 is a flow diagram of groupcast (or unicast) transmission withrepetition transmissions of V2V communication as per an aspect of anexample embodiment of the present disclosure.

FIG. 26 illustrates groupcast (or unicast) transmission with repetitiontransmissions of V2V communication as per an aspect of an exampleembodiment of the present disclosure.

FIG. 27 illustrates a procedure of groupcast (or unicast) transmissionwith repetition transmissions of V2V communication as per an aspect ofan example embodiment of the present disclosure.

FIG. 28 is a flow diagram of groupcast (or unicast) transmission withrepetition transmissions of V2V communication as per an aspect of anexample embodiment of the present disclosure.

FIG. 29 is a flow diagram of an aspect of an example embodiment of thepresent disclosure.

FIG. 30 is a flow diagram of an aspect of an example embodiment of thepresent disclosure.

DETAILED DESCRIPTION

In the present disclosure, various embodiments are presented as examplesof how the disclosed techniques may be implemented and/or how thedisclosed techniques may be practiced in environments and scenarios. Itwill be apparent to persons skilled in the relevant art that variouschanges in form and detail can be made therein without departing fromthe scope. In fact, after reading the description, it will be apparentto one skilled in the relevant art how to implement alternativeembodiments. The present embodiments should not be limited by any of thedescribed exemplary embodiments. The embodiments of the presentdisclosure will be described with reference to the accompanyingdrawings. Limitations, features, and/or elements from the disclosedexample embodiments may be combined to create further embodiments withinthe scope of the disclosure. Any figures which highlight thefunctionality and advantages, are presented for example purposes only.The disclosed architecture is sufficiently flexible and configurable,such that it may be utilized in ways other than that shown. For example,the actions listed in any flowchart may be re-ordered or only optionallyused in some embodiments.

Embodiments may be configured to operate as needed. The disclosedmechanism may be performed when certain criteria are met, for example,in a wireless device, a base station, a radio environment, a network, acombination of the above, and/or the like. Example criteria may bebased, at least in part, on for example, wireless device or network nodeconfigurations, traffic load, initial system set up, packet sizes,traffic characteristics, a combination of the above, and/or the like.When the one or more criteria are met, various example embodiments maybe applied. Therefore, it may be possible to implement exampleembodiments that selectively implement disclosed protocols.

A base station may communicate with a mix of wireless devices. Wirelessdevices and/or base stations may support multiple technologies, and/ormultiple releases of the same technology. Wireless devices may have somespecific capability(ies) depending on wireless device category and/orcapability(ies). When this disclosure refers to a base stationcommunicating with a plurality of wireless devices, this disclosure mayrefer to a subset of the total wireless devices in a coverage area. Thisdisclosure may refer to, for example, a plurality of wireless devices ofa given LTE or 5G release with a given capability and in a given sectorof the base station. The plurality of wireless devices in thisdisclosure may refer to a selected plurality of wireless devices, and/ora subset of total wireless devices in a coverage area which performaccording to disclosed methods, and/or the like. There may be aplurality of base stations or a plurality of wireless devices in acoverage area that may not comply with the disclosed methods, forexample, those wireless devices or base stations may perform based onolder releases of LTE or 5G technology.

In this disclosure, “a” and “an” and similar phrases are to beinterpreted as “at least one” and “one or more.” Similarly, any termthat ends with the suffix “(s)” is to be interpreted as “at least one”and “one or more.” In this disclosure, the term “may” is to beinterpreted as “may, for example.” In other words, the term “may” isindicative that the phrase following the term “may” is an example of oneof a multitude of suitable possibilities that may, or may not, beemployed by one or more of the various embodiments. The terms“comprises” and “consists of”, as used herein, enumerate one or morecomponents of the element being described. The term “comprises” isinterchangeable with “includes” and does not exclude unenumeratedcomponents from being included in the element being described. Bycontrast, “consists of” provides a complete enumeration of the one ormore components of the element being described. The term “based on”, asused herein, should be interpreted as “based at least in part on” ratherthan, for example, “based solely on”. The term “and/or” as used hereinrepresents any possible combination of enumerated elements. For example,“A, B, and/or C” may represent A; B; C; A and B; A and C; B and C; or A,B, and C.

If A and B are sets and every element of A is an element of B, A iscalled a subset of B. In this specification, only non-empty sets andsubsets are considered. For example, possible subsets of B = {cell1,cell2} are: {cell1}, {cell2}, and {cell1, cell2}. The phrase “based on”(or equally “based at least on”) is indicative that the phrase followingthe term “based on” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “in response to” (or equally “inresponse at least to”) is indicative that the phrase following thephrase “in response to” is an example of one of a multitude of suitablepossibilities that may, or may not, be employed to one or more of thevarious embodiments. The phrase “depending on” (or equally “depending atleast to”) is indicative that the phrase following the phrase “dependingon” is an example of one of a multitude of suitable possibilities thatmay, or may not, be employed to one or more of the various embodiments.The phrase “employing/using” (or equally “employing/using at least”) isindicative that the phrase following the phrase “employing/using” is anexample of one of a multitude of suitable possibilities that may, or maynot, be employed to one or more of the various embodiments.

The term configured may relate to the capacity of a device whether thedevice is in an operational or non-operational state. Configured mayrefer to specific settings in a device that effect the operationalcharacteristics of the device whether the device is in an operational ornon-operational state. In other words, the hardware, software, firmware,registers, memory values, and/or the like may be “configured” within adevice, whether the device is in an operational or nonoperational state,to provide the device with specific characteristics. Terms such as “acontrol message to cause in a device” may mean that a control messagehas parameters that may be used to configure specific characteristics ormay be used to implement certain actions in the device, whether thedevice is in an operational or non-operational state.

In this disclosure, parameters (or equally called, fields, orInformation elements: IEs) may comprise one or more information objects,and an information object may comprise one or more other objects. Forexample, if parameter (IE) N comprises parameter (IE) M, and parameter(IE) M comprises parameter (IE) K, and parameter (IE) K comprisesparameter (information element) J. Then, for example, N comprises K, andN comprises J. In an example embodiment, when one or more messagescomprise a plurality of parameters, it implies that a parameter in theplurality of parameters is in at least one of the one or more messages,but does not have to be in each of the one or more messages.

Many features presented are described as being optional through the useof “may” or the use of parentheses. For the sake of brevity andlegibility, the present disclosure does not explicitly recite each andevery permutation that may be obtained by choosing from the set ofoptional features. The present disclosure is to be interpreted asexplicitly disclosing all such permutations. For example, a systemdescribed as having three optional features may be embodied in sevenways, namely with just one of the three possible features, with any twoof the three possible features or with three of the three possiblefeatures.

Many of the elements described in the disclosed embodiments may beimplemented as modules. A module is defined here as an element thatperforms a defined function and has a defined interface to otherelements. The modules described in this disclosure may be implemented inhardware, software in combination with hardware, firmware, wetware (e.g.hardware with a biological element) or a combination thereof, which maybe behaviorally equivalent. For example, modules may be implemented as asoftware routine written in a computer language configured to beexecuted by a hardware machine (such as C, C++, Fortran, Java, Basic,Matlab or the like) or a modeling/simulation program such as Simulink,Stateflow, GNU Octave, or LabVIEWMathScript. It may be possible toimplement modules using physical hardware that incorporates discrete orprogrammable analog, digital and/or quantum hardware. Examples ofprogrammable hardware comprise: computers, microcontrollers,microprocessors, application-specific integrated circuits (ASICs); fieldprogrammable gate arrays (FPGAs); and complex programmable logic devices(CPLDs). Computers, microcontrollers and microprocessors are programmedusing languages such as assembly, C, C++ or the like. FPGAs, ASICs andCPLDs are often programmed using hardware description languages (HDL)such as VHSIC hardware description language (VHDL) or Verilog thatconfigure connections between internal hardware modules with lesserfunctionality on a programmable device. The mentioned technologies areoften used in combination to achieve the result of a functional module.

FIG. 1A illustrates an example of a mobile communication network 100 inwhich embodiments of the present disclosure may be implemented. Themobile communication network 100 may be, for example, a public landmobile network (PLMN) run by a network operator. As illustrated in FIG.1A, the mobile communication network 100 includes a core network (CN)102, a radio access network (RAN) 104, and a wireless device 106.

The CN 102 may provide the wireless device 106 with an interface to oneor more data networks (DNs), such as public DNs (e.g., the Internet),private DNs, and/or intra-operator DNs. As part of the interfacefunctionality, the CN 102 may set up end-to-end connections between thewireless device 106 and the one or more DNs, authenticate the wirelessdevice 106, and provide charging functionality.

The RAN 104 may connect the CN 102 to the wireless device 106 throughradio communications over an air interface. As part of the radiocommunications, the RAN 104 may provide scheduling, radio resourcemanagement, and retransmission protocols. The communication directionfrom the RAN 104 to the wireless device 106 over the air interface isknown as the downlink and the communication direction from the wirelessdevice 106 to the RAN 104 over the air interface is known as the uplink.Downlink transmissions may be separated from uplink transmissions usingfrequency division duplexing (FDD), time-division duplexing (TDD),and/or some combination of the two duplexing techniques.

The term wireless device may be used throughout this disclosure to referto and encompass any mobile device or fixed (non-mobile) device forwhich wireless communication is needed or usable. For example, awireless device may be a telephone, smart phone, tablet, computer,laptop, sensor, meter, wearable device, Internet of Things (IoT) device,vehicle road side unit (RSU), relay node, automobile, and/or anycombination thereof. The term wireless device encompasses otherterminology, including user equipment (UE), user terminal (UT), accessterminal (AT), mobile station, handset, wireless transmit and receiveunit (WTRU), and/or wireless communication device.

The RAN 104 may include one or more base stations (not shown). The termbase station may be used throughout this disclosure to refer to andencompass a Node B (associated with UMTS and/or 3G standards), anEvolved Node B (eNB, associated with E-UTRA and/or 4G standards), aremote radio head (RRH), a baseband processing unit coupled to one ormore RRHs, a repeater node or relay node used to extend the coveragearea of a donor node, a Next Generation Evolved Node B (ng-eNB), aGeneration Node B (gNB, associated with NR and/or 5G standards), anaccess point (AP, associated with, for example, WiFi or any othersuitable wireless communication standard), and/or any combinationthereof. A base station may comprise at least one gNB Central Unit(gNB-CU) and at least one a gNB Distributed Unit (gNB-DU).

A base station included in the RAN 104 may include one or more sets ofantennas for communicating with the wireless device 106 over the airinterface. For example, one or more of the base stations may includethree sets of antennas to respectively control three cells (or sectors).The size of a cell may be determined by a range at which a receiver(e.g., a base station receiver) can successfully receive thetransmissions from a transmitter (e.g., a wireless device transmitter)operating in the cell. Together, the cells of the base stations mayprovide radio coverage to the wireless device 106 over a wide geographicarea to support wireless device mobility.

In addition to three-sector sites, other implementations of basestations are possible. For example, one or more of the base stations inthe RAN 104 may be implemented as a sectored site with more or less thanthree sectors. One or more of the base stations in the RAN 104 may beimplemented as an access point, as a baseband processing unit coupled toseveral remote radio heads (RRHs), and/or as a repeater or relay nodeused to extend the coverage area of a donor node. A baseband processingunit coupled to RRHs may be part of a centralized or cloud RANarchitecture, where the baseband processing unit may be eithercentralized in a pool of baseband processing units or virtualized. Arepeater node may amplify and rebroadcast a radio signal received from adonor node. A relay node may perform the same/similar functions as arepeater node but may decode the radio signal received from the donornode to remove noise before amplifying and rebroadcasting the radiosignal.

The RAN 104 may be deployed as a homogenous network of macrocell basestations that have similar antenna patterns and similar high-leveltransmit powers. The RAN 104 may be deployed as a heterogeneous network.In heterogeneous networks, small cell base stations may be used toprovide small coverage areas, for example, coverage areas that overlapwith the comparatively larger coverage areas provided by macrocell basestations. The small coverage areas may be provided in areas with highdata traffic (or so-called “hotspots”) or in areas with weak macrocellcoverage. Examples of small cell base stations include, in order ofdecreasing coverage area, microcell base stations, picocell basestations, and femtocell base stations or home base stations.

The Third-Generation Partnership Project (3GPP) was formed in 1998 toprovide global standardization of specifications for mobilecommunication networks similar to the mobile communication network 100in FIG. 1A. To date, 3GPP has produced specifications for threegenerations of mobile networks: a third generation (3G) network known asUniversal Mobile Telecommunications System (UMTS), a fourth generation(4G) network known as Long-Term Evolution (LTE), and a fifth generation(5G) network known as 5G System (5GS). Embodiments of the presentdisclosure are described with reference to the RAN of a 3GPP 5G network,referred to as next-generation RAN (NG-RAN). Embodiments may beapplicable to RANs of other mobile communication networks, such as theRAN 104 in FIG. 1A, the RANs of earlier 3G and 4G networks, and those offuture networks yet to be specified (e.g., a 3GPP 6G network). NG-RANimplements 5G radio access technology known as New Radio (NR) and may beprovisioned to implement 4G radio access technology or other radioaccess technologies, including non-3GPP radio access technologies.

FIG. 1B illustrates another example mobile communication network 150 inwhich embodiments of the present disclosure may be implemented. Mobilecommunication network 150 may be, for example, a PLMN run by a networkoperator. As illustrated in FIG. 1B, mobile communication network 150includes a 5G core network (5G-CN) 152, an NG-RAN 154, and UEs 156A and156B (collectively UEs 156). These components may be implemented andoperate in the same or similar manner as corresponding componentsdescribed with respect to FIG. 1A.

The 5G-CN 152 provides the UEs 156 with an interface to one or more DNs,such as public DNs (e.g., the Internet), private DNs, and/orintra-operator DNs. As part of the interface functionality, the 5G-CN152 may set up end-to-end connections between the UEs 156 and the one ormore DNs, authenticate the UEs 156, and provide charging functionality.Compared to the CN of a 3GPP 4G network, the basis of the 5G-CN 152 maybe a service-based architecture. This means that the architecture of thenodes making up the 5G-CN 152 may be defined as network functions thatoffer services via interfaces to other network functions. The networkfunctions of the 5G-CN 152 may be implemented in several ways, includingas network elements on dedicated or shared hardware, as softwareinstances running on dedicated or shared hardware, or as virtualizedfunctions instantiated on a platform (e.g., a cloud-based platform).

As illustrated in FIG. 1B, the 5G-CN 152 includes an Access and MobilityManagement Function (AMF) 158A and a User Plane Function (UPF) 158B,which are shown as one component AMF/UPF 158 in FIG. 1B for ease ofillustration. The UPF 158B may serve as a gateway between the NG-RAN 154and the one or more DNs. The UPF 158B may perform functions such aspacket routing and forwarding, packet inspection and user plane policyrule enforcement, traffic usage reporting, uplink classification tosupport routing of traffic flows to the one or more DNs, quality ofservice (QoS) handling for the user plane (e.g., packet filtering,gating, uplink/downlink rate enforcement, and uplink trafficverification), downlink packet buffering, and downlink data notificationtriggering. The UPF 158B may serve as an anchor point forintra-/inter-Radio Access Technology (RAT) mobility, an externalprotocol (or packet) data unit (PDU) session point of interconnect tothe one or more DNs, and/or a branching point to support a multi-homedPDU session. The UEs 156 may be configured to receive services through aPDU session, which is a logical connection between a UE and a DN.

The AMF 158A may perform functions such as Non-Access Stratum (NAS)signaling termination, NAS signaling security, Access Stratum (AS)security control, inter-CN node signaling for mobility between 3GPPaccess networks, idle mode UE reachability (e.g., control and executionof paging retransmission), registration area management, intra-systemand inter-system mobility support, access authentication, accessauthorization including checking of roaming rights, mobility managementcontrol (subscription and policies), network slicing support, and/orsession management function (SMF) selection. NAS may refer to thefunctionality operating between a CN and a UE, and AS may refer to thefunctionality operating between the UE and a RAN.

The 5G-CN 152 may include one or more additional network functions thatare not shown in FIG. 1B for the sake of clarity. For example, the 5G-CN152 may include one or more of a Session Management Function (SMF), anNR Repository Function (NRF), a Policy Control Function (PCF), a NetworkExposure Function (NEF), a Unified Data Management (UDM), an ApplicationFunction (AF), and/or an Authentication Server Function (AUSF).

The NG-RAN 154 may connect the 5G-CN 152 to the UEs 156 through radiocommunications over the air interface. The NG-RAN 154 may include one ormore gNBs, illustrated as gNB 160A and gNB 160B (collectively gNBs 160)and/or one or more ng-eNBs, illustrated as ng-eNB 162A and ng-eNB 162B(collectively ng-eNBs 162). The gNBs 160 and ng-eNBs 162 may be moregenerically referred to as base stations. The gNBs 160 and ng-eNBs 162may include one or more sets of antennas for communicating with the UEs156 over an air interface. For example, one or more of the gNBs 160and/or one or more of the ng-eNBs 162 may include three sets of antennasto respectively control three cells (or sectors). Together, the cells ofthe gNBs 160 and the ng-eNBs 162 may provide radio coverage to the UEs156 over a wide geographic area to support UE mobility.

As shown in FIG. 1B, the gNBs 160 and/or the ng-eNBs 162 may beconnected to the 5G-CN 152 by means of an NG interface and to other basestations by an Xn interface. The NG and Xn interfaces may be establishedusing direct physical connections and/or indirect connections over anunderlying transport network, such as an internet protocol (IP)transport network. The gNBs 160 and/or the ng-eNBs 162 may be connectedto the UEs 156 by means of a Uu interface. For example, as illustratedin FIG. 1B, gNB 160A may be connected to the UE 156A by means of a Uuinterface. The NG, Xn, and Uu interfaces are associated with a protocolstack. The protocol stacks associated with the interfaces may be used bythe network elements in FIG. 1B to exchange data and signaling messagesand may include two planes: a user plane and a control plane. The userplane may handle data of interest to a user. The control plane mayhandle signaling messages of interest to the network elements.

The gNBs 160 and/or the ng-eNBs 162 may be connected to one or moreAMF/UPF functions of the 5G-CN 152, such as the AMF/UPF 158, by means ofone or more NG interfaces. For example, the gNB 160A may be connected tothe UPF 158B of the AMF/UPF 158 by means of an NG-User plane (NG-U)interface. The NG-U interface may provide delivery (e.g., non-guaranteeddelivery) of user plane PDUs between the gNB 160A and the UPF 158B. ThegNB 160A may be connected to the AMF 158A by means of an NG-Controlplane (NG-C) interface. The NG-C interface may provide, for example, NGinterface management, UE context management, UE mobility management,transport of NAS messages, paging, PDU session management, andconfiguration transfer and/or warning message transmission.

The gNBs 160 may provide NR user plane and control plane protocolterminations towards the UEs 156 over the Uu interface. For example, thegNB 160A may provide NR user plane and control plane protocolterminations toward the UE 156A over a Uu interface associated with afirst protocol stack. The ng-eNBs 162 may provide Evolved UMTSTerrestrial Radio Access (E-UTRA) user plane and control plane protocolterminations towards the UEs 156 over a Uu interface, where E-UTRArefers to the 3GPP 4G radio-access technology. For example, the ng-eNB162B may provide E-UTRA user plane and control plane protocolterminations towards the UE 156B over a Uu interface associated with asecond protocol stack.

The 5G-CN 152 was described as being configured to handle NR and 4Gradio accesses. It will be appreciated by one of ordinary skill in theart that it may be possible for NR to connect to a 4G core network in amode known as “non-standalone operation.” In non-standalone operation, a4G core network is used to provide (or at least support) control-planefunctionality (e.g., initial access, mobility, and paging). Althoughonly one AMF/UPF 158 is shown in FIG. 1B, one gNB or ng-eNB may beconnected to multiple AMF/UPF nodes to provide redundancy and/or to loadshare across the multiple AMF/UPF nodes.

As discussed, an interface (e.g., Uu, Xn, and NG interfaces) between thenetwork elements in FIG. 1B may be associated with a protocol stack thatthe network elements use to exchange data and signaling messages. Aprotocol stack may include two planes: a user plane and a control plane.The user plane may handle data of interest to a user, and the controlplane may handle signaling messages of interest to the network elements.

FIG. 2A and FIG. 2B respectively illustrate examples of NR user planeand NR control plane protocol stacks for the Uu interface that liesbetween a UE 210 and a gNB 220. The protocol stacks illustrated in FIG.2A and FIG. 2B may be the same or similar to those used for the Uuinterface between, for example, the UE 156A and the gNB 160A shown inFIG. 1B.

FIG. 2A illustrates a NR user plane protocol stack comprising fivelayers implemented in the UE 210 and the gNB 220. At the bottom of theprotocol stack, physical layers (PHYs) 211 and 221 may provide transportservices to the higher layers of the protocol stack and may correspondto layer 1 of the Open Systems Interconnection (OSI) model. The nextfour protocols above PHYs 211 and 221 comprise media access controllayers (MACs) 212 and 222, radio link control layers (RLCs) 213 and 223,packet data convergence protocol layers (PDCPs) 214 and 224, and servicedata application protocol layers (SDAPs) 215 and 225. Together, thesefour protocols may make up layer 2, or the data link layer, of the OSImodel.

FIG. 3 illustrates an example of services provided between protocollayers of the NR user plane protocol stack. Starting from the top ofFIG. 2A and FIG. 3 , the SDAPs 215 and 225 may perform QoS flowhandling. The UE 210 may receive services through a PDU session, whichmay be a logical connection between the UE 210 and a DN. The PDU sessionmay have one or more QoS flows. A UPF of a CN (e.g., the UPF 158B) maymap IP packets to the one or more QoS flows of the PDU session based onQoS requirements (e.g., in terms of delay, data rate, and/or errorrate). The SDAPs 215 and 225 may perform mapping/demapping between theone or more QoS flows and one or more data radio bearers. Themapping/de-mapping between the QoS flows and the data radio bearers maybe determined by the SDAP 225 at the gNB 220. The SDAP 215 at the UE 210may be informed of the mapping between the QoS flows and the data radiobearers through reflective mapping or control signaling received fromthe gNB 220. For reflective mapping, the SDAP 225 at the gNB 220 maymark the downlink packets with a QoS flow indicator (QFI), which may beobserved by the SDAP 215 at the UE 210 to determine themapping/de-mapping between the QoS flows and the data radio bearers.

The PDCPs 214 and 224 may perform header compression/decompression toreduce the amount of data that needs to be transmitted over the airinterface, ciphering/deciphering to prevent unauthorized decoding ofdata transmitted over the air interface, and integrity protection (toensure control messages originate from intended sources. The PDCPs 214and 224 may perform retransmissions of undelivered packets, in-sequencedelivery and reordering of packets, and removal of packets received induplicate due to, for example, an intra-gNB handover. The PDCPs 214 and224 may perform packet duplication to improve the likelihood of thepacket being received and, at the receiver, remove any duplicatepackets. Packet duplication may be useful for services that require highreliability.

Although not shown in FIG. 3 , PDCPs 214 and 224 may performmapping/demapping between a split radio bearer and RLC channels in adual connectivity scenario. Dual connectivity is a technique that allowsa UE to connect to two cells or, more generally, two cell groups: amaster cell group (MCG) and a secondary cell group (SCG). A split beareris when a single radio bearer, such as one of the radio bearers providedby the PDCPs 214 and 224 as a service to the SDAPs 215 and 225, ishandled by cell groups in dual connectivity. The PDCPs 214 and 224 maymap/de-map the split radio bearer between RLC channels belonging to cellgroups.

The RLCs 213 and 223 may perform segmentation, retransmission throughAutomatic Repeat Request (ARQ), and removal of duplicate data unitsreceived from MACs 212 and 222, respectively. The RLCs 213 and 223 maysupport three transmission modes: transparent mode (TM); unacknowledgedmode (UM); and acknowledged mode (AM). Based on the transmission mode anRLC is operating, the RLC may perform one or more of the notedfunctions. The RLC configuration may be per logical channel with nodependency on numerologies and/or Transmission Time Interval (TTI)durations. As shown in FIG. 3 , the RLCs 213 and 223 may provide RLCchannels as a service to PDCPs 214 and 224, respectively.

The MACs 212 and 222 may perform multiplexing/demultiplexing of logicalchannels and/or mapping between logical channels and transport channels.The multiplexing/demultiplexing may include multiplexing/demultiplexingof data units, belonging to the one or more logical channels, into/fromTransport Blocks (TBs) delivered to/from the PHYs 211 and 221. The MAC222 may be configured to perform scheduling, scheduling informationreporting, and priority handling between UEs by means of dynamicscheduling. Scheduling may be performed in the gNB 220 (at the MAC 222)for downlink and uplink. The MACs 212 and 222 may be configured toperform error correction through Hybrid Automatic Repeat Request (HARQ)(e.g., one HARQ entity per carrier in case of Carrier Aggregation (CA)),priority handling between logical channels of the UE 210 by means oflogical channel prioritization, and/or padding. The MACs 212 and 222 maysupport one or more numerologies and/or transmission timings. In anexample, mapping restrictions in a logical channel prioritization maycontrol which numerology and/or transmission timing a logical channelmay use. As shown in FIG. 3 , the MACs 212 and 222 may provide logicalchannels as a service to the RLCs 213 and 223.

The PHYs 211 and 221 may perform mapping of transport channels tophysical channels and digital and analog signal processing functions forsending and receiving information over the air interface. These digitaland analog signal processing functions may include, for example,coding/decoding and modulation/demodulation. The PHYs 211 and 221 mayperform multi-antenna mapping. As shown in FIG. 3 , the PHYs 211 and 221may provide one or more transport channels as a service to the MACs 212and 222.

FIG. 4A illustrates an example downlink data flow through the NR userplane protocol stack. FIG. 4A illustrates a downlink data flow of threeIP packets (n, n+1, and m) through the NR user plane protocol stack togenerate two TBs at the gNB 220. An uplink data flow through the NR userplane protocol stack may be similar to the downlink data flow depictedin FIG. 4A.

The downlink data flow of FIG. 4A begins when SDAP 225 receives thethree IP packets from one or more QoS flows and maps the three packetsto radio bearers. In FIG. 4A, the SDAP 225 maps IP packets n and n+1 toa first radio bearer 402 and maps IP packet m to a second radio bearer404. An SDAP header (labeled with an “H” in FIG. 4A) is added to an IPpacket. The data unit from/to a higher protocol layer is referred to asa service data unit (SDU) of the lower protocol layer and the data unitto/from a lower protocol layer is referred to as a protocol data unit(PDU) of the higher protocol layer. As shown in FIG. 4A, the data unitfrom the SDAP 225 is an SDU of lower protocol layer PDCP 224 and is aPDU of the SDAP 225.

The remaining protocol layers in FIG. 4A may perform their associatedfunctionality (e.g., with respect to FIG. 3 ), add correspondingheaders, and forward their respective outputs to the next lower layer.For example, the PDCP 224 may perform IP-header compression andciphering and forward its output to the RLC 223. The RLC 223 mayoptionally perform segmentation (e.g., as shown for IP packet m in FIG.4A) and forward its output to the MAC 222. The MAC 222 may multiplex anumber of RLC PDUs and may attach a MAC subheader to an RLC PDU to forma transport block. In NR, the MAC subheaders may be distributed acrossthe MAC PDU, as illustrated in FIG. 4A. In LTE, the MAC subheaders maybe entirely located at the beginning of the MAC PDU. The NR MAC PDUstructure may reduce processing time and associated latency because theMAC PDU subheaders may be computed before the full MAC PDU is assembled.

FIG. 4B illustrates an example format of a MAC subheader in a MAC PDU.The MAC subheader includes: an SDU length field for indicating thelength (e.g., in bytes) of the MAC SDU to which the MAC subheadercorresponds; a logical channel identifier (LCID) field for identifyingthe logical channel from which the MAC SDU originated to aid in thedemultiplexing process; a flag (F) for indicating the size of the SDUlength field; and a reserved bit (R) field for future use.

FIG. 4B further illustrates MAC control elements (CEs) inserted into theMAC PDU by a MAC, such as MAC 223 or MAC 222. For example, FIG. 4Billustrates two MAC CEs inserted into the MAC PDU. MAC CEs may beinserted at the beginning of a MAC PDU for downlink transmissions (asshown in FIG. 4B) and at the end of a MAC PDU for uplink transmissions.MAC CEs may be used for in-band control signaling. Example MAC CEsinclude: scheduling-related MAC CEs, such as buffer status reports andpower headroom reports; activation/deactivation MAC CEs, such as thosefor activation/deactivation of PDCP duplication detection, channel stateinformation (CSI) reporting, sounding reference signal (SRS)transmission, and prior configured components; discontinuous reception(DRX) related MAC CEs; timing advance MAC CEs; and random access relatedMAC CEs. A MAC CE may be preceded by a MAC subheader with a similarformat as described for MAC SDUs and may be identified with a reservedvalue in the LCID field that indicates the type of control informationincluded in the MAC CE.

Before describing the NR control plane protocol stack, logical channels,transport channels, and physical channels are first described as well asa mapping between the channel types. One or more of the channels may beused to carry out functions associated with the NR control planeprotocol stack described later below.

FIG. 5A and FIG. 5B illustrate, for downlink and uplink respectively, amapping between logical channels, transport channels, and physicalchannels. Information is passed through channels between the RLC, theMAC, and the PHY of the NR protocol stack. A logical channel may be usedbetween the RLC and the MAC and may be classified as a control channelthat carries control and configuration information in the NR controlplane or as a traffic channel that carries data in the NR user plane. Alogical channel may be classified as a dedicated logical channel that isdedicated to a specific UE or as a common logical channel that may beused by more than one UE. A logical channel may also be defined by thetype of information it carries. The set of logical channels defined byNR include, for example:

-   a paging control channel (PCCH) for carrying paging messages used to    page a UE whose location is not known to the network on a cell    level;-   a broadcast control channel (BCCH) for carrying system information    messages in the form of a master information block (MIB) and several    system information blocks (SIBs), wherein the system information    messages may be used by the UEs to obtain information about how a    cell is configured and how to operate within the cell;-   a common control channel (CCCH) for carrying control messages    together with random access;-   a dedicated control channel (DCCH) for carrying control messages    to/from a specific the UE to configure the UE; and-   a dedicated traffic channel (DTCH) for carrying user data to/from a    specific the UE.

Transport channels are used between the MAC and PHY layers and may bedefined by how the information they carry is transmitted over the airinterface. The set of transport channels defined by NR include, forexample:

-   a paging channel (PCH) for carrying paging messages that originated    from the PCCH;-   a broadcast channel (BCH) for carrying the MIB from the BCCH;-   a downlink shared channel (DL-SCH) for carrying downlink data and    signaling messages, including the SIBs from the BCCH;-   an uplink shared channel (UL-SCH) for carrying uplink data and    signaling messages; and-   a random access channel (RACH) for allowing a UE to contact the    network without any prior scheduling.

The PHY may use physical channels to pass information between processinglevels of the PHY. A physical channel may have an associated set oftime-frequency resources for carrying the information of one or moretransport channels. The PHY may generate control information to supportthe low-level operation of the PHY and provide the control informationto the lower levels of the PHY via physical control channels, known asL1/L2 control channels. The set of physical channels and physicalcontrol channels defined by NR include, for example:

-   a physical broadcast channel (PBCH) for carrying the MIB from the    BCH;-   a physical downlink shared channel (PDSCH) for carrying downlink    data and signaling messages from the DL-SCH, as well as paging    messages from the PCH;-   a physical downlink control channel (PDCCH) for carrying downlink    control information (DCI), which may include downlink scheduling    commands, uplink scheduling grants, and uplink power control    commands;-   a physical uplink shared channel (PUSCH) for carrying uplink data    and signaling messages from the UL-SCH and in some instances uplink    control information (UCI) as described below;-   a physical uplink control channel (PUCCH) for carrying UCI, which    may include HARQ acknowledgments, channel quality indicators (CQI),    pre-coding matrix indicators (PMI), rank indicators (RI), and    scheduling requests (SR); and-   a physical random access channel (PRACH) for random access.

Similar to the physical control channels, the physical layer generatesphysical signals to support the low-level operation of the physicallayer. As shown in FIG. 5A and FIG. 5B, the physical layer signalsdefined by NR include: primary synchronization signals (PSS), secondarysynchronization signals (SSS), channel state information referencesignals (CSI-RS), demodulation reference signals (DMRS), soundingreference signals (SRS), and phase-tracking reference signals (PT-RS).These physical layer signals will be described in greater detail below.

FIG. 2B illustrates an example NR control plane protocol stack. As shownin FIG. 2B, the NR control plane protocol stack may use the same/similarfirst four protocol layers as the example NR user plane protocol stack.These four protocol layers include the PHYs 211 and 221, the MACs 212and 222, the RLCs 213 and 223, and the PDCPs 214 and 224. Instead ofhaving the SDAPs 215 and 225 at the top of the stack as in the NR userplane protocol stack, the NR control plane stack has radio resourcecontrols (RRCs) 216 and 226 and NAS protocols 217 and 237 at the top ofthe NR control plane protocol stack.

The NAS protocols 217 and 237 may provide control plane functionalitybetween the UE 210 and the AMF 230 (e.g., the AMF 158A) or, moregenerally, between the UE 210 and the CN. The NAS protocols 217 and 237may provide control plane functionality between the UE 210 and the AMF230 via signaling messages, referred to as NAS messages. There is nodirect path between the UE 210 and the AMF 230 through which the NASmessages can be transported. The NAS messages may be transported usingthe AS of the Uu and NG interfaces. NAS protocols 217 and 237 mayprovide control plane functionality such as authentication, security,connection setup, mobility management, and session management.

The RRCs 216 and 226 may provide control plane functionality between theUE 210 and the gNB 220 or, more generally, between the UE 210 and theRAN. The RRCs 216 and 226 may provide control plane functionalitybetween the UE 210 and the gNB 220 via signaling messages, referred toas RRC messages. RRC messages may be transmitted between the UE 210 andthe RAN using signaling radio bearers and the same/similar PDCP, RLC,MAC, and PHY protocol layers. The MAC may multiplex control-plane anduser-plane data into the same transport block (TB). The RRCs 216 and 226may provide control plane functionality such as: broadcast of systeminformation related to AS and NAS; paging initiated by the CN or theRAN; establishment, maintenance and release of an RRC connection betweenthe UE 210 and the RAN; security functions including key management;establishment, configuration, maintenance and release of signaling radiobearers and data radio bearers; mobility functions; QoS managementfunctions; the UE measurement reporting and control of the reporting;detection of and recovery from radio link failure (RLF); and/or NASmessage transfer. As part of establishing an RRC connection, RRCs 216and 226 may establish an RRC context, which may involve configuringparameters for communication between the UE 210 and the RAN.

FIG. 6 is an example diagram showing RRC state transitions of a UE. TheUE may be the same or similar to the wireless device 106 depicted inFIG. 1A, the UE 210 depicted in FIG. 2A and FIG. 2B, or any otherwireless device described in the present disclosure. As illustrated inFIG. 6 , a UE may be in at least one of three RRC states: RRC connected602 (e.g., RRC_CONNECTED), RRC idle 604 (e.g., RRC_IDLE), and RRCinactive 606 (e.g., RRC_INACTIVE).

In RRC connected 602, the UE has an established RRC context and may haveat least one RRC connection with a base station. The base station may besimilar to one of the one or more base stations included in the RAN 104depicted in FIG. 1A, one of the gNBs 160 or ng-eNBs 162 depicted in FIG.1B, the gNB 220 depicted in FIG. 2A and FIG. 2B, or any other basestation described in the present disclosure. The base station with whichthe UE is connected may have the RRC context for the UE. The RRCcontext, referred to as the UE context, may comprise parameters forcommunication between the UE and the base station. These parameters mayinclude, for example: one or more AS contexts; one or more radio linkconfiguration parameters; bearer configuration information (e.g.,relating to a data radio bearer, signaling radio bearer, logicalchannel, QoS flow, and/or PDU session); security information; and/orPHY, MAC, RLC, PDCP, and/or SDAP layer configuration information. Whilein RRC connected 602, mobility of the UE may be managed by the RAN(e.g., the RAN 104 or the NG-RAN 154). The UE may measure the signallevels (e.g., reference signal levels) from a serving cell andneighboring cells and report these measurements to the base stationcurrently serving the UE. The UE’s serving base station may request ahandover to a cell of one of the neighboring base stations based on thereported measurements. The RRC state may transition from RRC connected602 to RRC idle 604 through a connection release procedure 608 or to RRCinactive 606 through a connection inactivation procedure 610.

In RRC idle 604, an RRC context may not be established for the UE. InRRC idle 604, the UE may not have an RRC connection with the basestation. While in RRC idle 604, the UE may be in a sleep state for themajority of the time (e.g., to conserve battery power). The UE may wakeup periodically (e.g., once in every discontinuous reception cycle) tomonitor for paging messages from the RAN. Mobility of the UE may bemanaged by the UE through a procedure known as cell reselection. The RRCstate may transition from RRC idle 604 to RRC connected 602 through aconnection establishment procedure 612, which may involve a randomaccess procedure as discussed in greater detail below.

In RRC inactive 606, the RRC context previously established ismaintained in the UE and the base station. This allows for a fasttransition to RRC connected 602 with reduced signaling overhead ascompared to the transition from RRC idle 604 to RRC connected 602. Whilein RRC inactive 606, the UE may be in a sleep state and mobility of theUE may be managed by the UE through cell reselection. The RRC state maytransition from RRC inactive 606 to RRC connected 602 through aconnection resume procedure 614 or to RRC idle 604 though a connectionrelease procedure 616 that may be the same as or similar to connectionrelease procedure 608.

An RRC state may be associated with a mobility management mechanism. InRRC idle 604 and RRC inactive 606, mobility is managed by the UE throughcell reselection. The purpose of mobility management in RRC idle 604 andRRC inactive 606 is to allow the network to be able to notify the UE ofan event via a paging message without having to broadcast the pagingmessage over the entire mobile communications network. The mobilitymanagement mechanism used in RRC idle 604 and RRC inactive 606 may allowthe network to track the UE on a cell-group level so that the pagingmessage may be broadcast over the cells of the cell group that the UEcurrently resides within instead of the entire mobile communicationnetwork. The mobility management mechanisms for RRC idle 604 and RRCinactive 606 track the UE on a cell-group level. They may do so usingdifferent granularities of grouping. For example, there may be threelevels of cell-grouping granularity: individual cells; cells within aRAN area identified by a RAN area identifier (RAI); and cells within agroup of RAN areas, referred to as a tracking area and identified by atracking area identifier (TAI).

Tracking areas may be used to track the UE at the CN level. The CN(e.g., the CN 102 or the 5G-CN 152) may provide the UE with a list ofTAIs associated with a UE registration area. If the UE moves, throughcell reselection, to a cell associated with a TAI not included in thelist of TAIs associated with the UE registration area, the UE mayperform a registration update with the CN to allow the CN to update theUE’s location and provide the UE with a new the UE registration area.

RAN areas may be used to track the UE at the RAN level. For a UE in RRCinactive 606 state, the UE may be assigned a RAN notification area. ARAN notification area may comprise one or more cell identities, a listof RAIs, or a list of TAIs. In an example, a base station may belong toone or more RAN notification areas. In an example, a cell may belong toone or more RAN notification areas. If the UE moves, through cellreselection, to a cell not included in the RAN notification areaassigned to the UE, the UE may perform a notification area update withthe RAN to update the UE’s RAN notification area.

A base station storing an RRC context for a UE or a last serving basestation of the UE may be referred to as an anchor base station. Ananchor base station may maintain an RRC context for the UE at leastduring a period of time that the UE stays in a RAN notification area ofthe anchor base station and/or during a period of time that the UE staysin RRC inactive 606.

A gNB, such as gNBs 160 in FIG. 1B, may be split in two parts: a centralunit (gNB-CU), and one or more distributed units (gNB-DU). A gNB-CU maybe coupled to one or more gNB-DUs using an F1 interface. The gNB-CU maycomprise the RRC, the PDCP, and the SDAP. A gNB-DU may comprise the RLC,the MAC, and the PHY.

In NR, the physical signals and physical channels (discussed withrespect to FIG. 5A and FIG. 5B) may be mapped onto orthogonal frequencydivisional multiplexing (OFDM) symbols. OFDM is a multicarriercommunication scheme that transmits data over F orthogonal subcarriers(or tones). Before transmission, the data may be mapped to a series ofcomplex symbols (e.g., M-quadrature amplitude modulation (M-QAM) orM-phase shift keying (M-PSK) symbols), referred to as source symbols,and divided into F parallel symbol streams. The F parallel symbolstreams may be treated as though they are in the frequency domain andused as inputs to an Inverse Fast Fourier Transform (IFFT) block thattransforms them into the time domain. The IFFT block may take in Fsource symbols at a time, one from each of the F parallel symbolstreams, and use each source symbol to modulate the amplitude and phaseof one of F sinusoidal basis functions that correspond to the Forthogonal subcarriers. The output of the IFFT block may be Ftime-domain samples that represent the summation of the F orthogonalsubcarriers. The F time-domain samples may form a single OFDM symbol.After some processing (e.g., addition of a cyclic prefix) andup-conversion, an OFDM symbol provided by the IFFT block may betransmitted over the air interface on a carrier frequency. The Fparallel symbol streams may be mixed using an FFT block before beingprocessed by the IFFT block. This operation produces Discrete FourierTransform (DFT)-precoded OFDM symbols and may be used by UEs in theuplink to reduce the peak to average power ratio (PAPR). Inverseprocessing may be performed on the OFDM symbol at a receiver using anFFT block to recover the data mapped to the source symbols.

FIG. 7 illustrates an example configuration of an NR frame into whichOFDM symbols are grouped. An NR frame may be identified by a systemframe number (SFN). The SFN may repeat with a period of 1024 frames. Asillustrated, one NR frame may be 10 milliseconds (ms) in duration andmay include 10 subframes that are 1 ms in duration. A subframe may bedivided into slots that include, for example, 14 OFDM symbols per slot.

The duration of a slot may depend on the numerology used for the OFDMsymbols of the slot. In NR, a flexible numerology is supported toaccommodate different cell deployments (e.g., cells with carrierfrequencies below 1 GHz up to cells with carrier frequencies in themm-wave range). A numerology may be defined in terms of subcarrierspacing and cyclic prefix duration. For a numerology in NR, subcarrierspacings may be scaled up by powers of two from a baseline subcarrierspacing of 15 kHz, and cyclic prefix durations may be scaled down bypowers of two from a baseline cyclic prefix duration of 4.7 µs. Forexample, NR defines numerologies with the following subcarrierspacing/cyclic prefix duration combinations: 15 kHz/4.7 µs; 30 kHz/2.3µs; 60 kHz/1.2 µs; 120 kHz/0.59 µs; and 240 kHz/0.29 µs.

A slot may have a fixed number of OFDM symbols (e.g., 14 OFDM symbols).A numerology with a higher subcarrier spacing has a shorter slotduration and, correspondingly, more slots per subframe. FIG. 7illustrates this numerology-dependent slot duration andslots-per-subframe transmission structure (the numerology with asubcarrier spacing of 240 kHz is not shown in FIG. 7 for ease ofillustration). A subframe in NR may be used as a numerology-independenttime reference, while a slot may be used as the unit upon which uplinkand downlink transmissions are scheduled. To support low latency,scheduling in NR may be decoupled from the slot duration and start atany OFDM symbol and last for as many symbols as needed for atransmission. These partial slot transmissions may be referred to asmini-slot or subslot transmissions.

FIG. 8 illustrates an example configuration of a slot in the time andfrequency domain for an NR carrier. The slot includes resource elements(REs) and resource blocks (RBs). An RE is the smallest physical resourcein NR. An RE spans one OFDM symbol in the time domain by one subcarrierin the frequency domain as shown in FIG. 8 . An RB spans twelveconsecutive REs in the frequency domain as shown in FIG. 8 . An NRcarrier may be limited to a width of 275 RBs or 275×12 = 3300subcarriers. Such a limitation, if used, may limit the NR carrier to 50,100, 200, and 400 MHz for subcarrier spacings of 15, 30, 60, and 120kHz, respectively, where the 400 MHz bandwidth may be set based on a 400MHz per carrier bandwidth limit.

FIG. 8 illustrates a single numerology being used across the entirebandwidth of the NR carrier. In other example configurations, multiplenumerologies may be supported on the same carrier.

NR may support wide carrier bandwidths (e.g., up to 400 MHz for asubcarrier spacing of 120 kHz). Not all UEs may be able to receive thefull carrier bandwidth (e.g., due to hardware limitations). Also,receiving the full carrier bandwidth may be prohibitive in terms of UEpower consumption. In an example, to reduce power consumption and/or forother purposes, a UE may adapt the size of the UE’s receive bandwidthbased on the amount of traffic the UE is scheduled to receive. This isreferred to as bandwidth adaptation.

NR defines bandwidth parts (BWPs) to support UEs not capable ofreceiving the full carrier bandwidth and to support bandwidthadaptation. In an example, a BWP may be defined by a subset ofcontiguous RBs on a carrier. A UE may be configured (e.g., via RRClayer) with one or more downlink BWPs and one or more uplink BWPs perserving cell (e.g., up to four downlink BWPs and up to four uplink BWPsper serving cell). At a given time, one or more of the configured BWPsfor a serving cell may be active. These one or more BWPs may be referredto as active BWPs of the serving cell. When a serving cell is configuredwith a secondary uplink carrier, the serving cell may have one or morefirst active BWPs in the uplink carrier and one or more second activeBWPs in the secondary uplink carrier.

For unpaired spectra, a downlink BWP from a set of configured downlinkBWPs may be linked with an uplink BWP from a set of configured uplinkBWPs if a downlink BWP index of the downlink BWP and an uplink BWP indexof the uplink BWP are the same. For unpaired spectra, a UE may expectthat a center frequency for a downlink BWP is the same as a centerfrequency for an uplink BWP.

For a downlink BWP in a set of configured downlink BWPs on a primarycell (PCell), a base station may configure a UE with one or more controlresource sets (CORESETs) for at least one search space. A search spaceis a set of locations in the time and frequency domains where the UE mayfind control information. The search space may be a UE-specific searchspace or a common search space (potentially usable by a plurality ofUEs). For example, a base station may configure a UE with a commonsearch space, on a PCell or on a primary secondary cell (PSCell), in anactive downlink BWP.

For an uplink BWP in a set of configured uplink BWPs, a BS may configurea UE with one or more resource sets for one or more PUCCH transmissions.A UE may receive downlink receptions (e.g., PDCCH or PDSCH) in adownlink BWP according to a configured numerology (e.g., subcarrierspacing and cyclic prefix duration) for the downlink BWP. The UE maytransmit uplink transmissions (e.g., PUCCH or PUSCH) in an uplink BWPaccording to a configured numerology (e.g., subcarrier spacing andcyclic prefix length for the uplink BWP).

One or more BWP indicator fields may be provided in Downlink ControlInformation (DCI). A value of a BWP indicator field may indicate whichBWP in a set of configured BWPs is an active downlink BWP for one ormore downlink receptions. The value of the one or more BWP indicatorfields may indicate an active uplink BWP for one or more uplinktransmissions.

A base station may semi-statically configure a UE with a defaultdownlink BWP within a set of configured downlink BWPs associated with aPCell. If the base station does not provide the default downlink BWP tothe UE, the default downlink BWP may be an initial active downlink BWP.The UE may determine which BWP is the initial active downlink BWP basedon a CORESET configuration obtained using the PBCH.

A base station may configure a UE with a BWP inactivity timer value fora PCell. The UE may start or restart a BWP inactivity timer at anyappropriate time. For example, the UE may start or restart the BWPinactivity timer (a) when the UE detects a DCI indicating an activedownlink BWP other than a default downlink BWP for a paired spectraoperation; or (b) when a UE detects a DCI indicating an active downlinkBWP or active uplink BWP other than a default downlink BWP or uplink BWPfor an unpaired spectra operation. If the UE does not detect DCI duringan interval of time (e.g., 1 ms or 0.5 ms), the UE may run the BWPinactivity timer toward expiration (for example, increment from zero tothe BWP inactivity timer value, or decrement from the BWP inactivitytimer value to zero). When the BWP inactivity timer expires, the UE mayswitch from the active downlink BWP to the default downlink BWP.

In an example, a base station may semi-statically configure a UE withone or more BWPs. A UE may switch an active BWP from a first BWP to asecond BWP in response to receiving a DCI indicating the second BWP asan active BWP and/or in response to an expiry of the BWP inactivitytimer (e.g., if the second BWP is the default BWP).

Downlink and uplink BWP switching (where BWP switching refers toswitching from a currently active BWP to a not currently active BWP) maybe performed independently in paired spectra. In unpaired spectra,downlink and uplink BWP switching may be performed simultaneously.Switching between configured BWPs may occur based on RRC signaling, DCI,expiration of a BWP inactivity timer, and/or an initiation of randomaccess.

FIG. 9 illustrates an example of bandwidth adaptation using threeconfigured BWPs for an NR carrier. A UE configured with the three BWPsmay switch from one BWP to another BWP at a switching point. In theexample illustrated in FIG. 9 , the BWPs include: a BWP 902 with abandwidth of 40 MHz and a subcarrier spacing of 15 kHz; a BWP 904 with abandwidth of 10 MHz and a subcarrier spacing of 15 kHz; and a BWP 906with a bandwidth of 20 MHz and a subcarrier spacing of 60 kHz. The BWP902 may be an initial active BWP, and the BWP 904 may be a default BWP.The UE may switch between BWPs at switching points. In the example ofFIG. 9 , the UE may switch from the BWP 902 to the BWP 904 at aswitching point 908. The switching at the switching point 908 may occurfor any suitable reason, for example, in response to an expiry of a BWPinactivity timer (indicating switching to the default BWP) and/or inresponse to receiving a DCI indicating BWP 904 as the active BWP. The UEmay switch at a switching point 910 from active BWP 904 to BWP 906 inresponse receiving a DCI indicating BWP 906 as the active BWP. The UEmay switch at a switching point 912 from active BWP 906 to BWP 904 inresponse to an expiry of a BWP inactivity timer and/or in responsereceiving a DCI indicating BWP 904 as the active BWP. The UE may switchat a switching point 914 from active BWP 904 to BWP 902 in responsereceiving a DCI indicating BWP 902 as the active BWP.

If a UE is configured for a secondary cell with a default downlink BWPin a set of configured downlink BWPs and a timer value, UE proceduresfor switching BWPs on a secondary cell may be the same/similar as thoseon a primary cell. For example, the UE may use the timer value and thedefault downlink BWP for the secondary cell in the same/similar manneras the UE would use these values for a primary cell.

To provide for greater data rates, two or more carriers can beaggregated and simultaneously transmitted to/from the same UE usingcarrier aggregation (CA). The aggregated carriers in CA may be referredto as component carriers (CCs). When CA is used, there are a number ofserving cells for the UE, one for a CC. The CCs may have threeconfigurations in the frequency domain.

FIG. 10A illustrates the three CA configurations with two CCs. In theintraband, contiguous configuration 1002, the two CCs are aggregated inthe same frequency band (frequency band A) and are located directlyadjacent to each other within the frequency band. In the intraband,non-contiguous configuration 1004, the two CCs are aggregated in thesame frequency band (frequency band A) and are separated in thefrequency band by a gap. In the interband configuration 1006, the twoCCs are located in frequency bands (frequency band A and frequency bandB).

In an example, up to 32 CCs may be aggregated. The aggregated CCs mayhave the same or different bandwidths, subcarrier spacing, and/orduplexing schemes (TDD or FDD). A serving cell for a UE using CA mayhave a downlink CC. For FDD, one or more uplink CCs may be optionallyconfigured for a serving cell. The ability to aggregate more downlinkcarriers than uplink carriers may be useful, for example, when the UEhas more data traffic in the downlink than in the uplink.

When CA is used, one of the aggregated cells for a UE may be referred toas a primary cell (PCell). The PCell may be the serving cell that the UEinitially connects to at RRC connection establishment, reestablishment,and/or handover. The PCell may provide the UE with NAS mobilityinformation and the security input. UEs may have different PCells. Inthe downlink, the carrier corresponding to the PCell may be referred toas the downlink primary CC (DL PCC). In the uplink, the carriercorresponding to the PCell may be referred to as the uplink primary CC(UL PCC). The other aggregated cells for the UE may be referred to assecondary cells (SCells). In an example, the SCells may be configuredafter the PCell is configured for the UE. For example, an SCell may beconfigured through an RRC Connection Reconfiguration procedure. In thedownlink, the carrier corresponding to an SCell may be referred to as adownlink secondary CC (DL SCC). In the uplink, the carrier correspondingto the SCell may be referred to as the uplink secondary CC (UL SCC).

Configured SCells for a UE may be activated and deactivated based on,for example, traffic and channel conditions. Deactivation of an SCellmay mean that PDCCH and PDSCH reception on the SCell is stopped andPUSCH, SRS, and CQI transmissions on the SCell are stopped. ConfiguredSCells may be activated and deactivated using a MAC CE with respect toFIG. 4B. For example, a MAC CE may use a bitmap (e.g., one bit perSCell) to indicate which SCells (e.g., in a subset of configured SCells)for the UE are activated or deactivated. Configured SCells may bedeactivated in response to an expiration of an SCell deactivation timer(e.g., one SCell deactivation timer per SCell).

Downlink control information, such as scheduling assignments andscheduling grants, for a cell may be transmitted on the cellcorresponding to the assignments and grants, which is known asself-scheduling. The DCI for the cell may be transmitted on anothercell, which is known as cross-carrier scheduling. Uplink controlinformation (e.g., HARQ acknowledgments and channel state feedback, suchas CQI, PMI, and/or RI) for aggregated cells may be transmitted on thePUCCH of the PCell. For a larger number of aggregated downlink CCs, thePUCCH of the PCell may become overloaded. Cells may be divided intomultiple PUCCH groups.

FIG. 10B illustrates an example of how aggregated cells may beconfigured into one or more PUCCH groups. A PUCCH group 1010 and a PUCCHgroup 1050 may include one or more downlink CCs, respectively. In theexample of FIG. 10B, the PUCCH group 1010 includes three downlink CCs: aPCell 1011, an SCell 1012, and an SCell 1013. The PUCCH group 1050includes three downlink CCs in the present example: a PCell 1051, anSCell 1052, and an SCell 1053. One or more uplink CCs may be configuredas a PCell 1021, an SCell 1022, and an SCell 1023. One or more otheruplink CCs may be configured as a primary Scell (PSCell) 1061, an SCell1062, and an SCell 1063. Uplink control information (UCI) related to thedownlink CCs of the PUCCH group 1010, shown as UCI 1031, UCI 1032, andUCI 1033, may be transmitted in the uplink of the PCell 1021. Uplinkcontrol information (UCI) related to the downlink CCs of the PUCCH group1050, shown as UCI 1071, UCI 1072, and UCI 1073, may be transmitted inthe uplink of the PSCell 1061. In an example, if the aggregated cellsdepicted in FIG. 10B were not divided into the PUCCH group 1010 and thePUCCH group 1050, a single uplink PCell to transmit UCI relating to thedownlink CCs, and the PCell may become overloaded. By dividingtransmissions of UCI between the PCell 1021 and the PSCell 1061,overloading may be prevented.

A cell, comprising a downlink carrier and optionally an uplink carrier,may be assigned with a physical cell ID and a cell index. The physicalcell ID or the cell index may identify a downlink carrier and/or anuplink carrier of the cell, for example, depending on the context inwhich the physical cell ID is used. A physical cell ID may be determinedusing a synchronization signal transmitted on a downlink componentcarrier. A cell index may be determined using RRC messages. In thedisclosure, a physical cell ID may be referred to as a carrier ID, and acell index may be referred to as a carrier index. For example, when thedisclosure refers to a first physical cell ID for a first downlinkcarrier, the disclosure may mean the first physical cell ID is for acell comprising the first downlink carrier. The same/similar concept mayapply to, for example, a carrier activation. When the disclosureindicates that a first carrier is activated, the specification may meanthat a cell comprising the first carrier is activated.

In CA, a multi-carrier nature of a PHY may be exposed to a MAC. In anexample, a HARQ entity may operate on a serving cell. A transport blockmay be generated per assignment/grant per serving cell. A transportblock and potential HARQ retransmissions of the transport block may bemapped to a serving cell.

In the downlink, a base station may transmit (e.g., unicast, multicast,and/or broadcast) one or more Reference Signals (RSs) to a UE (e.g.,PSS, SSS, CSI-RS, DMRS, and/or PT-RS, as shown in FIG. 5A). In theuplink, the UE may transmit one or more RSs to the base station (e.g.,DMRS, PT-RS, and/or SRS, as shown in FIG. 5B). The PSS and the SSS maybe transmitted by the base station and used by the UE to synchronize theUE to the base station. The PSS and the SSS may be provided in asynchronization signal (SS) / physical broadcast channel (PBCH) blockthat includes the PSS, the SSS, and the PBCH. The base station mayperiodically transmit a burst of SS/PBCH blocks.

FIG. 11A illustrates an example of an SS/PBCH block’s structure andlocation. A burst of SS/PBCH blocks may include one or more SS/PBCHblocks (e.g., 4 SS/PBCH blocks, as shown in FIG. 11A). Bursts may betransmitted periodically (e.g., every 2 frames or 20 ms). A burst may berestricted to a half-frame (e.g., a first half-frame having a durationof 5 ms). It will be understood that FIG. 11A is an example, and thatthese parameters (number of SS/PBCH blocks per burst, periodicity ofbursts, position of burst within the frame) may be configured based on,for example: a carrier frequency of a cell in which the SS/PBCH block istransmitted; a numerology or subcarrier spacing of the cell; aconfiguration by the network (e.g., using RRC signaling); or any othersuitable factor. In an example, the UE may assume a subcarrier spacingfor the SS/PBCH block based on the carrier frequency being monitored,unless the radio network configured the UE to assume a differentsubcarrier spacing.

The SS/PBCH block may span one or more OFDM symbols in the time domain(e.g., 4 OFDM symbols, as shown in the example of FIG. 11A) and may spanone or more subcarriers in the frequency domain (e.g., 240 contiguoussubcarriers). The PSS, the SSS, and the PBCH may have a common centerfrequency. The PSS may be transmitted first and may span, for example, 1OFDM symbol and 127 subcarriers. The SSS may be transmitted after thePSS (e.g., two symbols later) and may span 1 OFDM symbol and 127subcarriers. The PBCH may be transmitted after the PSS (e.g., across thenext 3 OFDM symbols) and may span 240 subcarriers.

The location of the SS/PBCH block in the time and frequency domains maynot be known to the UE (e.g., if the UE is searching for the cell). Tofind and select the cell, the UE may monitor a carrier for the PSS. Forexample, the UE may monitor a frequency location within the carrier. Ifthe PSS is not found after a certain duration (e.g., 20 ms), the UE maysearch for the PSS at a different frequency location within the carrier,as indicated by a synchronization raster. If the PSS is found at alocation in the time and frequency domains, the UE may determine, basedon a known structure of the SS/PBCH block, the locations of the SSS andthe PBCH, respectively. The SS/PBCH block may be a cell-defining SSblock (CD-SSB). In an example, a primary cell may be associated with aCD-SSB. The CD-SSB may be located on a synchronization raster. In anexample, a cell selection/search and/or reselection may be based on theCD-SSB.

The SS/PBCH block may be used by the UE to determine one or moreparameters of the cell. For example, the UE may determine a physicalcell identifier (PCI) of the cell based on the sequences of the PSS andthe SSS, respectively. The UE may determine a location of a frameboundary of the cell based on the location of the SS/PBCH block. Forexample, the SS/PBCH block may indicate that it has been transmitted inaccordance with a transmission pattern, wherein a SS/PBCH block in thetransmission pattern is a known distance from the frame boundary.

The PBCH may use a QPSK modulation and may use forward error correction(FEC). The FEC may use polar coding. One or more symbols spanned by thePBCH may carry one or more DMRSs for demodulation of the PBCH. The PBCHmay include an indication of a current system frame number (SFN) of thecell and/or a SS/PBCH block timing index. These parameters mayfacilitate time synchronization of the UE to the base station. The PBCHmay include a master information block (MIB) used to provide the UE withone or more parameters. The MIB may be used by the UE to locateremaining minimum system information (RMSI) associated with the cell.The RMSI may include a System Information Block Type 1 (SIB 1). The SIB1may contain information needed by the UE to access the cell. The UE mayuse one or more parameters of the MIB to monitor PDCCH, which may beused to schedule PDSCH. The PDSCH may include the SIB1. The SIB1 may bedecoded using parameters provided in the MIB. The PBCH may indicate anabsence of SIB1. Based on the PBCH indicating the absence of SIB1, theUE may be pointed to a frequency. The UE may search for an SS/PBCH blockat the frequency to which the UE is pointed.

The UE may assume that one or more SS/PBCH blocks transmitted with asame SS/PBCH block index are quasi co-located (QCLed) (e.g., having thesame/similar Doppler spread, Doppler shift, average gain, average delay,and/or spatial Rx parameters). The UE may not assume QCL for SS/PBCHblock transmissions having different SS/PBCH block indices.

SS/PBCH blocks (e.g., those within a half-frame) may be transmitted inspatial directions (e.g., using different beams that span a coveragearea of the cell). In an example, a first SS/PBCH block may betransmitted in a first spatial direction using a first beam, and asecond SS/PBCH block may be transmitted in a second spatial directionusing a second beam.

In an example, within a frequency span of a carrier, a base station maytransmit a plurality of SS/PBCH blocks. In an example, a first PCI of afirst SS/PBCH block of the plurality of SS/PBCH blocks may be differentfrom a second PCI of a second SS/PBCH block of the plurality of SS/PBCHblocks. The PCIs of SS/PBCH blocks transmitted in different frequencylocations may be different or the same.

The CSI-RS may be transmitted by the base station and used by the UE toacquire channel state information (CSI). The base station may configurethe UE with one or more CSI-RSs for channel estimation or any othersuitable purpose. The base station may configure a UE with one or moreof the same/similar CSI-RSs. The UE may measure the one or more CSI-RSs.The UE may estimate a downlink channel state and/or generate a CSIreport based on the measuring of the one or more downlink CSI-RSs. TheUE may provide the CSI report to the base station. The base station mayuse feedback provided by the UE (e.g., the estimated downlink channelstate) to perform link adaptation.

The base station may semi-statically configure the UE with one or moreCSI-RS resource sets. A CSI-RS resource may be associated with alocation in the time and frequency domains and a periodicity. The basestation may selectively activate and/or deactivate a CSI-RS resource.The base station may indicate to the UE that a CSI-RS resource in theCSI-RS resource set is activated and/or deactivated.

The base station may configure the UE to report CSI measurements. Thebase station may configure the UE to provide CSI reports periodically,aperiodically, or semi-persistently. For periodic CSI reporting, the UEmay be configured with a timing and/or periodicity of a plurality of CSIreports. For aperiodic CSI reporting, the base station may request a CSIreport. For example, the base station may command the UE to measure aconfigured CSI-RS resource and provide a CSI report relating to themeasurements. For semi-persistent CSI reporting, the base station mayconfigure the UE to transmit periodically, and selectively activate ordeactivate the periodic reporting. The base station may configure the UEwith a CSI-RS resource set and CSI reports using RRC signaling.

The CSI-RS configuration may comprise one or more parameters indicating,for example, up to 32 antenna ports. The UE may be configured to employthe same OFDM symbols for a downlink CSI-RS and a control resource set(CORESET) when the downlink CSI-RS and CORESET are spatially QCLed andresource elements associated with the downlink CSI-RS are outside of thephysical resource blocks (PRBs) configured for the CORESET. The UE maybe configured to employ the same OFDM symbols for downlink CSI-RS andSS/PBCH blocks when the downlink CSI-RS and SS/PBCH blocks are spatiallyQCLed and resource elements associated with the downlink CSI-RS areoutside of PRBs configured for the SS/PBCH blocks.

Downlink DMRSs may be transmitted by a base station and used by a UE forchannel estimation. For example, the downlink DMRS may be used forcoherent demodulation of one or more downlink physical channels (e.g.,PDSCH). An NR network may support one or more variable and/orconfigurable DMRS patterns for data demodulation. At least one downlinkDMRS configuration may support a front-loaded DMRS pattern. Afront-loaded DMRS may be mapped over one or more OFDM symbols (e.g., oneor two adjacent OFDM symbols). A base station may semi-staticallyconfigure the UE with a number (e.g. a maximum number) of front-loadedDMRS symbols for PDSCH. A DMRS configuration may support one or moreDMRS ports. For example, for single user-MIMO, a DMRS configuration maysupport up to eight orthogonal downlink DMRS ports per UE. Formultiuser-MIMO, a DMRS configuration may support up to 4 orthogonaldownlink DMRS ports per UE. A radio network may support (e.g., at leastfor CP-OFDM) a common DMRS structure for downlink and uplink, wherein aDMRS location, a DMRS pattern, and/or a scrambling sequence may be thesame or different. The base station may transmit a downlink DMRS and acorresponding PDSCH using the same precoding matrix. The UE may use theone or more downlink DMRSs for coherent demodulation/channel estimationof the PDSCH.

In an example, a transmitter (e.g., a base station) may use a precodermatrices for a part of a transmission bandwidth. For example, thetransmitter may use a first precoder matrix for a first bandwidth and asecond precoder matrix for a second bandwidth. The first precoder matrixand the second precoder matrix may be different based on the firstbandwidth being different from the second bandwidth. The UE may assumethat a same precoding matrix is used across a set of PRBs. The set ofPRBs may be denoted as a precoding resource block group (PRG).

A PDSCH may comprise one or more layers. The UE may assume that at leastone symbol with DMRS is present on a layer of the one or more layers ofthe PDSCH. A higher layer may configure up to 3 DMRSs for the PDSCH.

Downlink PT-RS may be transmitted by a base station and used by a UE forphase-noise compensation. Whether a downlink PT-RS is present or not maydepend on an RRC configuration. The presence and/or pattern of thedownlink PT-RS may be configured on a UE-specific basis using acombination of RRC signaling and/or an association with one or moreparameters employed for other purposes (e.g., modulation and codingscheme (MCS)), which may be indicated by DCI. When configured, a dynamicpresence of a downlink PT-RS may be associated with one or more DCIparameters comprising at least MCS. An NR network may support aplurality of PT-RS densities defined in the time and/or frequencydomains. When present, a frequency domain density may be associated withat least one configuration of a scheduled bandwidth. The UE may assume asame precoding for a DMRS port and a PT-RS port. A number of PT-RS portsmay be fewer than a number of DMRS ports in a scheduled resource.Downlink PT-RS may be confined in the scheduled time/frequency durationfor the UE. Downlink PT-RS may be transmitted on symbols to facilitatephase tracking at the receiver.

The UE may transmit an uplink DMRS to a base station for channelestimation. For example, the base station may use the uplink DMRS forcoherent demodulation of one or more uplink physical channels. Forexample, the UE may transmit an uplink DMRS with a PUSCH and/or a PUCCH.The uplink DM-RS may span a range of frequencies that is similar to arange of frequencies associated with the corresponding physical channel.The base station may configure the UE with one or more uplink DMRSconfigurations. At least one DMRS configuration may support afront-loaded DMRS pattern. The front-loaded DMRS may be mapped over oneor more OFDM symbols (e.g., one or two adjacent OFDM symbols). One ormore uplink DMRSs may be configured to transmit at one or more symbolsof a PUSCH and/or a PUCCH. The base station may semi-staticallyconfigure the UE with a number (e.g. maximum number) of front-loadedDMRS symbols for the PUSCH and/or the PUCCH, which the UE may use toschedule a single-symbol DMRS and/or a double-symbol DMRS. An NR networkmay support (e.g., for cyclic prefix orthogonal frequency divisionmultiplexing (CP-OFDM)) a common DMRS structure for downlink and uplink,wherein a DMRS location, a DMRS pattern, and/or a scrambling sequencefor the DMRS may be the same or different.

A PUSCH may comprise one or more layers, and the UE may transmit atleast one symbol with DMRS present on a layer of the one or more layersof the PUSCH. In an example, a higher layer may configure up to threeDMRSs for the PUSCH.

Uplink PT-RS (which may be used by a base station for phase trackingand/or phase-noise compensation) may or may not be present depending onan RRC configuration of the UE. The presence and/or pattern of uplinkPT-RS may be configured on a UE-specific basis by a combination of RRCsignaling and/or one or more parameters employed for other purposes(e.g., Modulation and Coding Scheme (MCS)), which may be indicated byDCI. When configured, a dynamic presence of uplink PT-RS may beassociated with one or more DCI parameters comprising at least MCS. Aradio network may support a plurality of uplink PT-RS densities definedin time/frequency domain. When present, a frequency domain density maybe associated with at least one configuration of a scheduled bandwidth.The UE may assume a same precoding for a DMRS port and a PT-RS port. Anumber of PT-RS ports may be fewer than a number of DMRS ports in ascheduled resource. For example, uplink PT-RS may be confined in thescheduled time/frequency duration for the UE.

SRS may be transmitted by a UE to a base station for channel stateestimation to support uplink channel dependent scheduling and/or linkadaptation. SRS transmitted by the UE may allow a base station toestimate an uplink channel state at one or more frequencies. A schedulerat the base station may employ the estimated uplink channel state toassign one or more resource blocks for an uplink PUSCH transmission fromthe UE. The base station may semi-statically configure the UE with oneor more SRS resource sets. For an SRS resource set, the base station mayconfigure the UE with one or more SRS resources. An SRS resource setapplicability may be configured by a higher layer (e.g., RRC) parameter.For example, when a higher layer parameter indicates beam management, anSRS resource in a SRS resource set of the one or more SRS resource sets(e.g., with the same/similar time domain behavior, periodic, aperiodic,and/or the like) may be transmitted at a time instant (e.g.,simultaneously). The UE may transmit one or more SRS resources in SRSresource sets. An NR network may support aperiodic, periodic and/orsemi-persistent SRS transmissions. The UE may transmit SRS resourcesbased on one or more trigger types, wherein the one or more triggertypes may comprise higher layer signaling (e.g., RRC) and/or one or moreDCI formats. In an example, at least one DCI format may be employed forthe UE to select at least one of one or more configured SRS resourcesets. An SRS trigger type 0 may refer to an SRS triggered based on ahigher layer signaling. An SRS trigger type 1 may refer to an SRStriggered based on one or more DCI formats. In an example, when PUSCHand SRS are transmitted in a same slot, the UE may be configured totransmit SRS after a transmission of a PUSCH and a corresponding uplinkDMRS.

The base station may semi-statically configure the UE with one or moreSRS configuration parameters indicating at least one of following: a SRSresource configuration identifier; a number of SRS ports; time domainbehavior of an SRS resource configuration (e.g., an indication ofperiodic, semi-persistent, or aperiodic SRS); slot, mini-slot, and/orsubframe level periodicity; offset for a periodic and/or an aperiodicSRS resource; a number of OFDM symbols in an SRS resource; a startingOFDM symbol of an SRS resource; an SRS bandwidth; a frequency hoppingbandwidth; a cyclic shift; and/or an SRS sequence ID.

An antenna port is defined such that the channel over which a symbol onthe antenna port is conveyed can be inferred from the channel over whichanother symbol on the same antenna port is conveyed. If a first symboland a second symbol are transmitted on the same antenna port, thereceiver may infer the channel (e.g., fading gain, multipath delay,and/or the like) for conveying the second symbol on the antenna port,from the channel for conveying the first symbol on the antenna port. Afirst antenna port and a second antenna port may be referred to as quasico-located (QCLed) if one or more large-scale properties of the channelover which a first symbol on the first antenna port is conveyed may beinferred from the channel over which a second symbol on a second antennaport is conveyed. The one or more large-scale properties may comprise atleast one of: a delay spread; a Doppler spread; a Doppler shift; anaverage gain; an average delay; and/or spatial Receiving (Rx)parameters.

Channels that use beamforming require beam management. Beam managementmay comprise beam measurement, beam selection, and beam indication. Abeam may be associated with one or more reference signals. For example,a beam may be identified by one or more beamformed reference signals.The UE may perform downlink beam measurement based on downlink referencesignals (e.g., a channel state information reference signal (CSI-RS))and generate a beam measurement report. The UE may perform the downlinkbeam measurement procedure after an RRC connection is set up with a basestation.

FIG. 11B illustrates an example of channel state information referencesignals (CSI-RSs) that are mapped in the time and frequency domains. Asquare shown in FIG. 11B may span a resource block (RB) within abandwidth of a cell. A base station may transmit one or more RRCmessages comprising CSI-RS resource configuration parameters indicatingone or more CSI-RSs. One or more of the following parameters may beconfigured by higher layer signaling (e.g., RRC and/or MAC signaling)for a CSI-RS resource configuration: a CSI-RS resource configurationidentity, a number of CSI-RS ports, a CSI-RS configuration (e.g., symboland resource element (RE) locations in a subframe), a CSI-RS subframeconfiguration (e.g., subframe location, offset, and periodicity in aradio frame), a CSI-RS power parameter, a CSI-RS sequence parameter, acode division multiplexing (CDM) type parameter, a frequency density, atransmission comb, quasi co-location (QCL) parameters (e.g.,QCL-scramblingidentity, crs-portscount, mbsfn-subframeconfiglist,csi-rs-configZPid, qcl-csi-rs-configNZPid), and/or other radio resourceparameters.

The three beams illustrated in FIG. 11B may be configured for a UE in aUE-specific configuration. Three beams are illustrated in FIG. 11B (beam#1, beam #2, and beam #3), more or fewer beams may be configured. Beam#1 may be allocated with CSI-RS 1101 that may be transmitted in one ormore subcarriers in an RB of a first symbol. Beam #2 may be allocatedwith CSI-RS 1102 that may be transmitted in one or more subcarriers inan RB of a second symbol. Beam #3 may be allocated with CSI-RS 1103 thatmay be transmitted in one or more subcarriers in an RB of a thirdsymbol. By using frequency division multiplexing (FDM), a base stationmay use other subcarriers in a same RB (for example, those that are notused to transmit CSI-RS 1101) to transmit another CSI-RS associated witha beam for another UE. By using time domain multiplexing (TDM), beamsused for the UE may be configured such that beams for the UE use symbolsfrom beams of other UEs.

CSI-RSs such as those illustrated in FIG. 11B (e.g., CSI-RS 1101, 1102,1103) may be transmitted by the base station and used by the UE for oneor more measurements. For example, the UE may measure a reference signalreceived power (RSRP) of configured CSI-RS resources. The base stationmay configure the UE with a reporting configuration and the UE mayreport the RSRP measurements to a network (for example, via one or morebase stations) based on the reporting configuration. In an example, thebase station may determine, based on the reported measurement results,one or more transmission configuration indication (TCI) statescomprising a number of reference signals. In an example, the basestation may indicate one or more TCI states to the UE (e.g., via RRCsignaling, a MAC CE, and/or a DCI). The UE may receive a downlinktransmission with a receive (Rx) beam determined based on the one ormore TCI states. In an example, the UE may or may not have a capabilityof beam correspondence. If the UE has the capability of beamcorrespondence, the UE may determine a spatial domain filter of atransmit (Tx) beam based on a spatial domain filter of the correspondingRx beam. If the UE does not have the capability of beam correspondence,the UE may perform an uplink beam selection procedure to determine thespatial domain filter of the Tx beam. The UE may perform the uplink beamselection procedure based on one or more sounding reference signal (SRS)resources configured to the UE by the base station. The base station mayselect and indicate uplink beams for the UE based on measurements of theone or more SRS resources transmitted by the UE.

In a beam management procedure, a UE may assess (e.g., measure) achannel quality of one or more beam pair links, a beam pair linkcomprising a transmitting beam transmitted by a base station and areceiving beam received by the UE. Based on the assessment, the UE maytransmit a beam measurement report indicating one or more beam pairquality parameters comprising, e.g., one or more beam identifications(e.g., a beam index, a reference signal index, or the like), RSRP, aprecoding matrix indicator (PMI), a channel quality indicator (CQI),and/or a rank indicator (RI).

FIG. 12A illustrates examples of three downlink beam managementprocedures: P1, P2, and P3. Procedure P1 may enable a UE measurement ontransmit (Tx) beams of a transmission reception point (TRP) (or multipleTRPs), e.g., to support a selection of one or more base station Tx beamsand/or UE Rx beams (shown as ovals in the top row and bottom row,respectively, of P1). Beamforming at a TRP may comprise a Tx beam sweepfor a set of beams (shown, in the top rows of P1 and P2, as ovalsrotated in a counter-clockwise direction indicated by the dashed arrow).Beamforming at a UE may comprise an Rx beam sweep for a set of beams(shown, in the bottom rows of P1 and P3, as ovals rotated in a clockwisedirection indicated by the dashed arrow). Procedure P2 may be used toenable a UE measurement on Tx beams of a TRP (shown, in the top row ofP2, as ovals rotated in a counter-clockwise direction indicated by thedashed arrow). The UE and/or the base station may perform procedure P2using a smaller set of beams than is used in procedure P1, or usingnarrower beams than the beams used in procedure P1. This may be referredto as beam refinement. The UE may perform procedure P3 for Rx beamdetermination by using the same Tx beam at the base station and sweepingan Rx beam at the UE.

FIG. 12B illustrates examples of three uplink beam managementprocedures: U1, U2, and U3. Procedure U1 may be used to enable a basestation to perform a measurement on Tx beams of a UE, e.g., to support aselection of one or more UE Tx beams and/or base station Rx beams (shownas ovals in the top row and bottom row, respectively, of U1).Beamforming at the UE may include, e.g., a Tx beam sweep from a set ofbeams (shown in the bottom rows of U1 and U3 as ovals rotated in aclockwise direction indicated by the dashed arrow). Beamforming at thebase station may include, e.g., an Rx beam sweep from a set of beams(shown, in the top rows of U1 and U2, as ovals rotated in acounter-clockwise direction indicated by the dashed arrow). Procedure U2may be used to enable the base station to adjust its Rx beam when the UEuses a fixed Tx beam. The UE and/or the base station may performprocedure U2 using a smaller set of beams than is used in procedure P1,or using narrower beams than the beams used in procedure P1. This may bereferred to as beam refinement The UE may perform procedure U3 to adjustits Tx beam when the base station uses a fixed Rx beam.

A UE may initiate a beam failure recovery (BFR) procedure based ondetecting a beam failure. The UE may transmit a BFR request (e.g., apreamble, a UCI, an SR, a MAC CE, and/or the like) based on theinitiating of the BFR procedure. The UE may detect the beam failurebased on a determination that a quality of beam pair link(s) of anassociated control channel is unsatisfactory (e.g., having an error ratehigher than an error rate threshold, a received signal power lower thana received signal power threshold, an expiration of a timer, and/or thelike).

The UE may measure a quality of a beam pair link using one or morereference signals (RSs) comprising one or more SS/PBCH blocks, one ormore CSI-RS resources, and/or one or more demodulation reference signals(DMRSs). A quality of the beam pair link may be based on one or more ofa block error rate (BLER), an RSRP value, a signal to interference plusnoise ratio (SINR) value, a reference signal received quality (RSRQ)value, and/or a CSI value measured on RS resources. The base station mayindicate that an RS resource is quasi co-located (QCLed) with one ormore DM-RSs of a channel (e.g., a control channel, a shared datachannel, and/or the like). The RS resource and the one or more DMRSs ofthe channel may be QCLed when the channel characteristics (e.g., Dopplershift, Doppler spread, average delay, delay spread, spatial Rxparameter, fading, and/or the like) from a transmission via the RSresource to the UE are similar or the same as the channelcharacteristics from a transmission via the channel to the UE.

A network (e.g., a gNB and/or an ng-eNB of a network) and/or the UE mayinitiate a random access procedure. A UE in an RRC_IDLE state and/or anRRC_INACTIVE state may initiate the random access procedure to request aconnection setup to a network. The UE may initiate the random accessprocedure from an RRC_CONNECTED state. The UE may initiate the randomaccess procedure to request uplink resources (e.g., for uplinktransmission of an SR when there is no PUCCH resource available) and/oracquire uplink timing (e.g., when uplink synchronization status isnon-synchronized). The UE may initiate the random access procedure torequest one or more system information blocks (SIBs) (e.g., other systeminformation such as SIB2, SIB3, and/or the like). The UE may initiatethe random access procedure for a beam failure recovery request. Anetwork may initiate a random access procedure for a handover and/or forestablishing time alignment for an SCell addition.

FIG. 13A illustrates a four-step contention-based random accessprocedure. Prior to initiation of the procedure, a base station maytransmit a configuration message 1310 to the UE. The procedureillustrated in FIG. 13A comprises transmission of four messages: a Msg 11311, a Msg 2 1312, a Msg 3 1313, and a Msg 4 1314. The Msg 1 1311 mayinclude and/or be referred to as a preamble (or a random accesspreamble). The Msg 2 1312 may include and/or be referred to as a randomaccess response (RAR).

The configuration message 1310 may be transmitted, for example, usingone or more RRC messages. The one or more RRC messages may indicate oneor more random access channel (RACH) parameters to the UE. The one ormore RACH parameters may comprise at least one of following: generalparameters for one or more random access procedures (e.g.,RACH-configGeneral); cell-specific parameters (e.g., RACH-ConfigCommon);and/or dedicated parameters (e.g., RACH-configDedicated). The basestation may broadcast or multicast the one or more RRC messages to oneor more UEs. The one or more RRC messages may be UE-specific (e.g.,dedicated RRC messages transmitted to a UE in an RRC_CONNECTED stateand/or in an RRC_INACTIVE state). The UE may determine, based on the oneor more RACH parameters, a time-frequency resource and/or an uplinktransmit power for transmission of the Msg 1 1311 and/or the Msg 3 1313.Based on the one or more RACH parameters, the UE may determine areception timing and a downlink channel for receiving the Msg 2 1312 andthe Msg 4 1314.

The one or more RACH parameters provided in the configuration message1310 may indicate one or more Physical RACH (PRACH) occasions availablefor transmission of the Msg 1 1311. The one or more PRACH occasions maybe predefined. The one or more RACH parameters may indicate one or moreavailable sets of one or more PRACH occasions (e.g., prach-ConfigIndex).The one or more RACH parameters may indicate an association between (a)one or more PRACH occasions and (b) one or more reference signals. Theone or more RACH parameters may indicate an association between (a) oneor more preambles and (b) one or more reference signals. The one or morereference signals may be SS/PBCH blocks and/or CSI-RSs. For example, theone or more RACH parameters may indicate a number of SS/PBCH blocksmapped to a PRACH occasion and/or a number of preambles mapped to aSS/PBCH blocks.

The one or more RACH parameters provided in the configuration message1310 may be used to determine an uplink transmit power of Msg 1 1311and/or Msg 3 1313. For example, the one or more RACH parameters mayindicate a reference power for a preamble transmission (e.g., a receivedtarget power and/or an initial power of the preamble transmission).There may be one or more power offsets indicated by the one or more RACHparameters. For example, the one or more RACH parameters may indicate: apower ramping step; a power offset between SSB and CSI-RS; a poweroffset between transmissions of the Msg 1 1311 and the Msg 3 1313;and/or a power offset value between preamble groups. The one or moreRACH parameters may indicate one or more thresholds based on which theUE may determine at least one reference signal (e.g., an SSB and/orCSI-RS) and/or an uplink carrier (e.g., a normal uplink (NUL) carrierand/or a supplemental uplink (SUL) carrier).

The Msg 1 1311 may include one or more preamble transmissions (e.g., apreamble transmission and one or more preamble retransmissions). An RRCmessage may be used to configure one or more preamble groups (e.g.,group A and/or group B). A preamble group may comprise one or morepreambles. The UE may determine the preamble group based on a pathlossmeasurement and/or a size of the Msg 3 1313. The UE may measure an RSRPof one or more reference signals (e.g., SSBs and/or CSI-RSs) anddetermine at least one reference signal having an RSRP above an RSRPthreshold (e.g., rsrp-ThresholdSSB and/or rsrp-ThresholdCSI-RS). The UEmay select at least one preamble associated with the one or morereference signals and/or a selected preamble group, for example, if theassociation between the one or more preambles and the at least onereference signal is configured by an RRC message.

The UE may determine the preamble based on the one or more RACHparameters provided in the configuration message 1310. For example, theUE may determine the preamble based on a pathloss measurement, an RSRPmeasurement, and/or a size of the Msg 3 1313. As another example, theone or more RACH parameters may indicate: a preamble format; a maximumnumber of preamble transmissions; and/or one or more thresholds fordetermining one or more preamble groups (e.g., group A and group B). Abase station may use the one or more RACH parameters to configure the UEwith an association between one or more preambles and one or morereference signals (e.g., SSBs and/or CSI-RSs). If the association isconfigured, the UE may determine the preamble to include in Msg 1 1311based on the association. The Msg 1 1311 may be transmitted to the basestation via one or more PRACH occasions. The UE may use one or morereference signals (e.g., SSBs and/or CSI-RSs) for selection of thepreamble and for determining of the PRACH occasion. One or more RACHparameters (e.g., ra-ssb-OccasionMskIndex and/or ra-OccasionList) mayindicate an association between the PRACH occasions and the one or morereference signals.

The UE may perform a preamble retransmission if no response is receivedfollowing a preamble transmission. The UE may increase an uplinktransmit power for the preamble retransmission. The UE may select aninitial preamble transmit power based on a pathloss measurement and/or atarget received preamble power configured by the network. The UE maydetermine to retransmit a preamble and may ramp up the uplink transmitpower. The UE may receive one or more RACH parameters (e.g.,PREAMBLE_POWER_RAMPING_STEP) indicating a ramping step for the preambleretransmission. The ramping step may be an amount of incrementalincrease in uplink transmit power for a retransmission. The UE may rampup the uplink transmit power if the UE determines a reference signal(e.g., SSB and/or CSI-RS) that is the same as a previous preambletransmission. The UE may count a number of preamble transmissions and/orretransmissions (e.g., PREAMBLE_TRANSMISSION_COUNTER). The UE maydetermine that a random access procedure completed unsuccessfully, forexample, if the number of preamble transmissions exceeds a thresholdconfigured by the one or more RACH parameters (e.g., preambleTransMax).

The Msg 2 1312 received by the UE may include an RAR. In some scenarios,the Msg 2 1312 may include multiple RARs corresponding to multiple UEs.The Msg 2 1312 may be received after or in response to the transmittingof the Msg 1 1311. The Msg 2 1312 may be scheduled on the DL-SCH andindicated on a PDCCH using a random access RNTI (RA-RNTI). The Msg 21312 may indicate that the Msg 1 1311 was received by the base station.The Msg 2 1312 may include a time-alignment command that may be used bythe UE to adjust the UE’s transmission timing, a scheduling grant fortransmission of the Msg 3 1313, and/or a Temporary Cell RNTI (TC-RNTI).After transmitting a preamble, the UE may start a time window (e.g.,ra-ResponseWindow) to monitor a PDCCH for the Msg 2 1312. The UE maydetermine when to start the time window based on a PRACH occasion thatthe UE uses to transmit the preamble. For example, the UE may start thetime window one or more symbols after a last symbol of the preamble(e.g., at a first PDCCH occasion from an end of a preambletransmission). The one or more symbols may be determined based on anumerology. The PDCCH may be in a common search space (e.g., aType1-PDCCH common search space) configured by an RRC message. The UEmay identify the RAR based on a Radio Network Temporary Identifier(RNTI). RNTIs may be used depending on one or more events initiating therandom access procedure. The UE may use random access RNTI (RA-RNTI).The RA-RNTI may be associated with PRACH occasions in which the UEtransmits a preamble. For example, the UE may determine the RA-RNTIbased on: an OFDM symbol index; a slot index; a frequency domain index;and/or a UL carrier indicator of the PRACH occasions. An example ofRA-RNTI may be as follows:

-   RA-RNTI= 1 + s_id + 14 × t_id + 14 × 80 × f_id + 14 × 80 × 8 ×    ul_carrier_id where s_id may be an index of a first OFDM symbol of    the PRACH occasion (e.g., 0 ≤ s_id < 14), t_id may be an index of a    first slot of the PRACH occasion in a system frame (e.g., 0 ≤ t_id <    80), f_id may be an index of the PRACH occasion in the frequency    domain (e.g., 0 ≤ f_id < 8), and ul_carrier_id may be a UL carrier    used for a preamble transmission (e.g., 0 for an NUL carrier, and 1    for an SUL carrier).

The UE may transmit the Msg 3 1313 in response to a successful receptionof the Msg 2 1312 (e.g., using resources identified in the Msg 2 1312).The Msg 3 1313 may be used for contention resolution in, for example,the contention-based random access procedure illustrated in FIG. 13A. Insome scenarios, a plurality of UEs may transmit a same preamble to abase station and the base station may provide an RAR that corresponds toa UE. Collisions may occur if the plurality of UEs interpret the RAR ascorresponding to themselves. Contention resolution (e.g., using the Msg3 1313 and the Msg 4 1314) may be used to increase the likelihood thatthe UE does not incorrectly use an identity of another the UE. Toperform contention resolution, the UE may include a device identifier inthe Msg 3 1313 (e.g., a C-RNTI if assigned, a TC-RNTI included in theMsg 2 1312, and/or any other suitable identifier).

The Msg 4 1314 may be received after or in response to the transmittingof the Msg 3 1313. If a C-RNTI was included in the Msg 3 1313, the basestation will address the UE on the PDCCH using the C-RNTI. If the UE’sunique C-RNTI is detected on the PDCCH, the random access procedure isdetermined to be successfully completed. If a TC-RNTI is included in theMsg 3 1313 (e.g., if the UE is in an RRC_IDLE state or not otherwiseconnected to the base station), Msg 4 1314 will be received using aDL-SCH associated with the TC-RNTI. If a MAC PDU is successfully decodedand a MAC PDU comprises the UE contention resolution identity MAC CEthat matches or otherwise corresponds with the CCCH SDU sent (e.g.,transmitted) in Msg 3 1313, the UE may determine that the contentionresolution is successful and/or the UE may determine that the randomaccess procedure is successfully completed.

The UE may be configured with a supplementary uplink (SUL) carrier and anormal uplink (NUL) carrier. An initial access (e.g., random accessprocedure) may be supported in an uplink carrier. For example, a basestation may configure the UE with two separate RACH configurations: onefor an SUL carrier and the other for an NUL carrier. For random accessin a cell configured with an SUL carrier, the network may indicate whichcarrier to use (NUL or SUL). The UE may determine the SUL carrier, forexample, if a measured quality of one or more reference signals is lowerthan a broadcast threshold. Uplink transmissions of the random accessprocedure (e.g., the Msg 1 1311 and/or the Msg 3 1313) may remain on theselected carrier. The UE may switch an uplink carrier during the randomaccess procedure (e.g., between the Msg 1 1311 and the Msg 3 1313) inone or more cases. For example, the UE may determine and/or switch anuplink carrier for the Msg 1 1311 and/or the Msg 3 1313 based on achannel clear assessment (e.g., a listen-before-talk).

FIG. 13B illustrates a two-step contention-free random access procedure.Similar to the four-step contention-based random access procedureillustrated in FIG. 13A, a base station may, prior to initiation of theprocedure, transmit a configuration message 1320 to the UE. Theconfiguration message 1320 may be analogous in some respects to theconfiguration message 1310. The procedure illustrated in FIG. 13Bcomprises transmission of two messages: a Msg 1 1321 and a Msg 2 1322.The Msg 1 1321 and the Msg 2 1322 may be analogous in some respects tothe Msg 1 1311 and a Msg 2 1312 illustrated in FIG. 13A, respectively.As will be understood from FIGS. 13A and 13B, the contention-free randomaccess procedure may not include messages analogous to the Msg 3 1313and/or the Msg 4 1314.

The contention-free random access procedure illustrated in FIG. 13B maybe initiated for a beam failure recovery, other SI request, SCelladdition, and/or handover. For example, a base station may indicate orassign to the UE the preamble to be used for the Msg 1 1321. The UE mayreceive, from the base station via PDCCH and/or RRC, an indication of apreamble (e.g., ra-PreambleIndex).

After transmitting a preamble, the UE may start a time window (e.g.,ra-ResponseWindow) to monitor a PDCCH for the RAR. In the event of abeam failure recovery request, the base station may configure the UEwith a separate time window and/or a separate PDCCH in a search spaceindicated by an RRC message (e.g., recoverySearchSpaceId). The UE maymonitor for a PDCCH transmission addressed to a Cell RNTI (C-RNTI) onthe search space. In the contention-free random access procedureillustrated in FIG. 13B, the UE may determine that a random accessprocedure successfully completes after or in response to transmission ofMsg 1 1321 and reception of a corresponding Msg 2 1322. The UE maydetermine that a random access procedure successfully completes, forexample, if a PDCCH transmission is addressed to a C-RNTI. The UE maydetermine that a random access procedure successfully completes, forexample, if the UE receives an RAR comprising a preamble identifiercorresponding to a preamble transmitted by the UE and/or the RARcomprises a MAC sub-PDU with the preamble identifier. The UE maydetermine the response as an indication of an acknowledgement for an SIrequest.

FIG. 13C illustrates another two-step random access procedure. Similarto the random access procedures illustrated in FIGS. 13A and 13B, a basestation may, prior to initiation of the procedure, transmit aconfiguration message 1330 to the UE. The configuration message 1330 maybe analogous in some respects to the configuration message 1310 and/orthe configuration message 1320. The procedure illustrated in FIG. 13Ccomprises transmission of two messages: a Msg A 1331 and a Msg B 1332.

Msg A 1320 may be transmitted in an uplink transmission by the UE. Msg A1320 may comprise one or more transmissions of a preamble 1341 and/orone or more transmissions of a transport block 1342. The transport block1342 may comprise contents that are similar and/or equivalent to thecontents of the Msg 3 1313 illustrated in FIG. 13A. The transport block1342 may comprise UCI (e.g., an SR, a HARQ ACK/NACK, and/or the like).The UE may receive the Msg B 1350 after or in response to transmittingthe Msg A 1320. The Msg B 1350 may comprise contents that are similarand/or equivalent to the contents of the Msg 2 1312 (e.g., an RAR)illustrated in FIGS. 13A and 13B and/or the Msg 4 1314 illustrated inFIG. 13A.

The UE may initiate the two-step random access procedure in FIG. 13C forlicensed spectrum and/or unlicensed spectrum. The UE may determine,based on one or more factors, whether to initiate the two-step randomaccess procedure. The one or more factors may be: a radio accesstechnology in use (e.g., LTE, NR, and/or the like); whether the UE hasvalid TA or not; a cell size; the UE’s RRC state; a type of spectrum(e.g., licensed vs. unlicensed); and/or any other suitable factors.

The UE may determine, based on two-step RACH parameters included in theconfiguration message 1330, a radio resource and/or an uplink transmitpower for the preamble 1341 and/or the transport block 1342 included inthe Msg A 1331. The RACH parameters may indicate a modulation and codingschemes (MCS), a time-frequency resource, and/or a power control for thepreamble 1341 and/or the transport block 1342. A time-frequency resourcefor transmission of the preamble 1341 (e.g., a PRACH) and atime-frequency resource for transmission of the transport block 1342(e.g., a PUSCH) may be multiplexed using FDM, TDM, and/or CDM. The RACHparameters may enable the UE to determine a reception timing and adownlink channel for monitoring for and/or receiving Msg B 1350.

The transport block 1342 may comprise data (e.g., delay-sensitive data),an identifier of the UE, security information, and/or device information(e.g., an International Mobile Subscriber Identity (IMSI)). The basestation may transmit the Msg B 1332 as a response to the Msg A 1331. TheMsg B 1332 may comprise at least one of following: a preambleidentifier; a timing advance command; a power control command; an uplinkgrant (e.g., a radio resource assignment and/or an MCS); a UE identifierfor contention resolution; and/or an RNTI (e.g., a C-RNTI or a TC-RNTI).The UE may determine that the two-step random access procedure issuccessfully completed if: a preamble identifier in the Msg B 1332 ismatched to a preamble transmitted by the UE; and/or the identifier ofthe UE in Msg B 1332 is matched to the identifier of the UE in the Msg A1331 (e.g., the transport block 1342).

A UE and a base station may exchange control signaling. The controlsignaling may be referred to as L1/L2 control signaling and mayoriginate from the PHY layer (e.g., layer 1) and/or the MAC layer (e.g.,layer 2). The control signaling may comprise downlink control signalingtransmitted from the base station to the UE and/or uplink controlsignaling transmitted from the UE to the base station.

The downlink control signaling may comprise: a downlink schedulingassignment; an uplink scheduling grant indicating uplink radio resourcesand/or a transport format; a slot format information; a preemptionindication; a power control command; and/or any other suitablesignaling. The UE may receive the downlink control signaling in apayload transmitted by the base station on a physical downlink controlchannel (PDCCH). The payload transmitted on the PDCCH may be referred toas downlink control information (DCI). In some scenarios, the PDCCH maybe a group common PDCCH (GC-PDCCH) that is common to a group of UEs.

A base station may attach one or more cyclic redundancy check (CRC)parity bits to a DCI in order to facilitate detection of transmissionerrors. When the DCI is intended for a UE (or a group of the UEs), thebase station may scramble the CRC parity bits with an identifier of theUE (or an identifier of the group of the UEs). Scrambling the CRC paritybits with the identifier may comprise Modulo-2 addition (or an exclusiveOR operation) of the identifier value and the CRC parity bits. Theidentifier may comprise a 16-bit value of a radio network temporaryidentifier (RNTI).

DCIs may be used for different purposes. A purpose may be indicated bythe type of RNTI used to scramble the CRC parity bits. For example, aDCI having CRC parity bits scrambled with a paging RNTI (P-RNTI) mayindicate paging information and/or a system information changenotification. The P-RNTI may be predefined as “FFFE” in hexadecimal. ADCI having CRC parity bits scrambled with a system information RNTI(SI-RNTI) may indicate a broadcast transmission of the systeminformation. The SI-RNTI may be predefined as “FFFF” in hexadecimal. ADCI having CRC parity bits scrambled with a random access RNTI (RA-RNTI)may indicate a random access response (RAR). A DCI having CRC paritybits scrambled with a cell RNTI (C-RNTI) may indicate a dynamicallyscheduled unicast transmission and/or a triggering of PDCCH-orderedrandom access. A DCI having CRC parity bits scrambled with a temporarycell RNTI (TC-RNTI) may indicate a contention resolution (e.g., a Msg 3analogous to the Msg 3 1313 illustrated in FIG. 13A). Other RNTIsconfigured to the UE by a base station may comprise a ConfiguredScheduling RNTI (CS-RNTI), a Transmit Power Control-PUCCH RNTI(TPC-PUCCH-RNTI), a Transmit Power Control-PUSCH RNTI (TPC-PUSCH-RNTI),a Transmit Power Control-SRS RNTI (TPC-SRS-RNTI), an Interruption RNTI(INT-RNTI), a Slot Format Indication RNTI (SFI-RNTI), a Semi-PersistentCSI RNTI (SP-CSI-RNTI), a Modulation and Coding Scheme Cell RNTI(MCS-C-RNTI), and/or the like.

Depending on the purpose and/or content of a DCI, the base station maytransmit the DCIs with one or more DCI formats. For example, DCI format0_0 may be used for scheduling of PUSCH in a cell. DCI format 0_0 may bea fallback DCI format (e.g., with compact DCI payloads). DCI format 0_1may be used for scheduling of PUSCH in a cell (e.g., with more DCIpayloads than DCI format 0_0). DCI format 1_0 may be used for schedulingof PDSCH in a cell. DCI format 1_0 may be a fallback DCI format (e.g.,with compact DCI payloads). DCI format 1_1 may be used for scheduling ofPDSCH in a cell (e.g., with more DCI payloads than DCI format 1_0). DCIformat 2_0 may be used for providing a slot format indication to a groupof UEs. DCI format 2_1 may be used for notifying a group of UEs of aphysical resource block and/or OFDM symbol where the UE may assume notransmission is intended to the UE. DCI format 2_2 may be used fortransmission of a transmit power control (TPC) command for PUCCH orPUSCH. DCI format 2_3 may be used for transmission of a group of TPCcommands for SRS transmissions by one or more UEs. DCI format(s) for newfunctions may be defined in future releases. DCI formats may havedifferent DCI sizes, or may share the same DCI size.

After scrambling a DCI with a RNTI, the base station may process the DCIwith channel coding (e.g., polar coding), rate matching, scramblingand/or QPSK modulation. A base station may map the coded and modulatedDCI on resource elements used and/or configured for a PDCCH. Based on apayload size of the DCI and/or a coverage of the base station, the basestation may transmit the DCI via a PDCCH occupying a number ofcontiguous control channel elements (CCEs). The number of the contiguousCCEs (referred to as aggregation level) may be 1, 2, 4, 8, 16, and/orany other suitable number. A CCE may comprise a number (e.g., 6) ofresource-element groups (REGs). A REG may comprise a resource block inan OFDM symbol. The mapping of the coded and modulated DCI on theresource elements may be based on mapping of CCEs and REGs (e.g.,CCE-to-REG mapping).

FIG. 14A illustrates an example of CORESET configurations for abandwidth part. The base station may transmit a DCI via a PDCCH on oneor more control resource sets (CORESETs). A CORESET may comprise atime-frequency resource in which the UE tries to decode a DCI using oneor more search spaces. The base station may configure a size and alocation of the CORESET in the time-frequency domain. In the example ofFIG. 14A, a first CORESET 1401 and a second CORESET 1402 occur at thefirst symbol in a slot. The first CORESET 1401 overlaps with the secondCORESET 1402 in the frequency domain. A third CORESET 1403 occurs at athird symbol in the slot. A fourth CORESET 1404 occurs at the seventhsymbol in the slot. CORESETs may have a different number of resourceblocks in frequency domain.

FIG. 14B illustrates an example of a CCE-to-REG mapping for DCItransmission on a CORESET and PDCCH processing. The CCE-to-REG mappingmay be an interleaved mapping (e.g., for the purpose of providingfrequency diversity) or a non-interleaved mapping (e.g., for thepurposes of facilitating interference coordination and/orfrequency-selective transmission of control channels). The base stationmay perform different or same CCE-to-REG mapping on different CORESETs.A CORESET may be associated with a CCE-to-REG mapping by RRCconfiguration. A CORESET may be configured with an antenna port quasico-location (QCL) parameter. The antenna port QCL parameter may indicateQCL information of a demodulation reference signal (DMRS) for PDCCHreception in the CORESET.

The base station may transmit, to the UE, RRC messages comprisingconfiguration parameters of one or more CORESETs and one or more searchspace sets. The configuration parameters may indicate an associationbetween a search space set and a CORESET. A search space set maycomprise a set of PDCCH candidates formed by CCEs at a given aggregationlevel. The configuration parameters may indicate: a number of PDCCHcandidates to be monitored per aggregation level; a PDCCH monitoringperiodicity and a PDCCH monitoring pattern; one or more DCI formats tobe monitored by the UE; and/or whether a search space set is a commonsearch space set or a UE-specific search space set. A set of CCEs in thecommon search space set may be predefined and known to the UE. A set ofCCEs in the UE-specific search space set may be configured based on theUE’s identity (e.g., C-RNTI).

As shown in FIG. 14B, the UE may determine a time-frequency resource fora CORESET based on RRC messages. The UE may determine a CCE-to-REGmapping (e.g., interleaved or non-interleaved, and/or mappingparameters) for the CORESET based on configuration parameters of theCORESET. The UE may determine a number (e.g., at most 10) of searchspace sets configured on the CORESET based on the RRC messages. The UEmay monitor a set of PDCCH candidates according to configurationparameters of a search space set. The UE may monitor a set of PDCCHcandidates in one or more CORESETs for detecting one or more DCIs.Monitoring may comprise decoding one or more PDCCH candidates of the setof the PDCCH candidates according to the monitored DCI formats.Monitoring may comprise decoding a DCI content of one or more PDCCHcandidates with possible (or configured) PDCCH locations, possible (orconfigured) PDCCH formats (e.g., number of CCEs, number of PDCCHcandidates in common search spaces, and/or number of PDCCH candidates inthe UE-specific search spaces) and possible (or configured) DCI formats.The decoding may be referred to as blind decoding. The UE may determinea DCI as valid for the UE, in response to CRC checking (e.g., scrambledbits for CRC parity bits of the DCI matching a RNTI value). The UE mayprocess information contained in the DCI (e.g., a scheduling assignment,an uplink grant, power control, a slot format indication, a downlinkpreemption, and/or the like).

The UE may transmit uplink control signaling (e.g., uplink controlinformation (UCI)) to a base station. The uplink control signaling maycomprise hybrid automatic repeat request (HARQ) acknowledgements forreceived DL-SCH transport blocks. The UE may transmit the HARQacknowledgements after receiving a DL-SCH transport block. Uplinkcontrol signaling may comprise channel state information (CSI)indicating channel quality of a physical downlink channel. The UE maytransmit the CSI to the base station. The base station, based on thereceived CSI, may determine transmission format parameters (e.g.,comprising multi-antenna and beamforming schemes) for a downlinktransmission. Uplink control signaling may comprise scheduling requests(SR). The UE may transmit an SR indicating that uplink data is availablefor transmission to the base station. The UE may transmit a UCI (e.g.,HARQ acknowledgements (HARQ-ACK), CSI report, SR, and the like) via aphysical uplink control channel (PUCCH) or a physical uplink sharedchannel (PUSCH). The UE may transmit the uplink control signaling via aPUCCH using one of several PUCCH formats.

There may be five PUCCH formats and the UE may determine a PUCCH formatbased on a size of the UCI (e.g., a number of uplink symbols of UCItransmission and a number of UCI bits). PUCCH format 0 may have a lengthof one or two OFDM symbols and may include two or fewer bits. The UE maytransmit UCI in a PUCCH resource using PUCCH format 0 if thetransmission is over one or two symbols and the number of HARQ-ACKinformation bits with positive or negative SR (HARQ-ACK/SR bits) is oneor two. PUCCH format 1 may occupy a number between four and fourteenOFDM symbols and may include two or fewer bits. The UE may use PUCCHformat 1 if the transmission is four or more symbols and the number ofHARQ-ACK/SR bits is one or two. PUCCH format 2 may occupy one or twoOFDM symbols and may include more than two bits. The UE may use PUCCHformat 2 if the transmission is over one or two symbols and the numberof UCI bits is two or more. PUCCH format 3 may occupy a number betweenfour and fourteen OFDM symbols and may include more than two bits. TheUE may use PUCCH format 3 if the transmission is four or more symbols,the number of UCI bits is two or more and PUCCH resource does notinclude an orthogonal cover code. PUCCH format 4 may occupy a numberbetween four and fourteen OFDM symbols and may include more than twobits. The UE may use PUCCH format 4 if the transmission is four or moresymbols, the number of UCI bits is two or more and the PUCCH resourceincludes an orthogonal cover code.

The base station may transmit configuration parameters to the UE for aplurality of PUCCH resource sets using, for example, an RRC message. Theplurality of PUCCH resource sets (e.g., up to four sets) may beconfigured on an uplink BWP of a cell. A PUCCH resource set may beconfigured with a PUCCH resource set index, a plurality of PUCCHresources with a PUCCH resource being identified by a PUCCH resourceidentifier (e.g., pucch-Resourceid), and/or a number (e.g. a maximumnumber) of UCI information bits the UE may transmit using one of theplurality of PUCCH resources in the PUCCH resource set. When configuredwith a plurality of PUCCH resource sets, the UE may select one of theplurality of PUCCH resource sets based on a total bit length of the UCIinformation bits (e.g., HARQ-ACK, SR, and/or CSI). If the total bitlength of UCI information bits is two or fewer, the UE may select afirst PUCCH resource set having a PUCCH resource set index equal to “0”.If the total bit length of UCI information bits is greater than two andless than or equal to a first configured value, the UE may select asecond PUCCH resource set having a PUCCH resource set index equal to“1”. If the total bit length of UCI information bits is greater than thefirst configured value and less than or equal to a second configuredvalue, the UE may select a third PUCCH resource set having a PUCCHresource set index equal to “2”. If the total bit length of UCIinformation bits is greater than the second configured value and lessthan or equal to a third value (e.g., 1406), the UE may select a fourthPUCCH resource set having a PUCCH resource set index equal to “3”.

After determining a PUCCH resource set from a plurality of PUCCHresource sets, the UE may determine a PUCCH resource from the PUCCHresource set for UCI (HARQ-ACK, CSI, and/or SR) transmission. The UE maydetermine the PUCCH resource based on a PUCCH resource indicator in aDCI (e.g., with a DCI format 1_0 or DCI for 1_1) received on a PDCCH. Athree-bit PUCCH resource indicator in the DCI may indicate one of eightPUCCH resources in the PUCCH resource set. Based on the PUCCH resourceindicator, the UE may transmit the UCI (HARQ-ACK, CSI and/or SR) using aPUCCH resource indicated by the PUCCH resource indicator in the DCI.

FIG. 15 illustrates an example of a wireless device 1502 incommunication with a base station 1504 in accordance with embodiments ofthe present disclosure. The wireless device 1502 and base station 1504may be part of a mobile communication network, such as the mobilecommunication network 100 illustrated in FIG. 1A, the mobilecommunication network 150 illustrated in FIG. 1B, or any othercommunication network. Only one wireless device 1502 and one basestation 1504 are illustrated in FIG. 15 , but it will be understood thata mobile communication network may include more than one UE and/or morethan one base station, with the same or similar configuration as thoseshown in FIG. 15 .

The base station 1504 may connect the wireless device 1502 to a corenetwork (not shown) through radio communications over the air interface(or radio interface) 1506. The communication direction from the basestation 1504 to the wireless device 1502 over the air interface 1506 isknown as the downlink, and the communication direction from the wirelessdevice 1502 to the base station 1504 over the air interface is known asthe uplink. Downlink transmissions may be separated from uplinktransmissions using FDD, TDD, and/or some combination of the twoduplexing techniques.

In the downlink, data to be sent to the wireless device 1502 from thebase station 1504 may be provided to the processing system 1508 of thebase station 1504. The data may be provided to the processing system1508 by, for example, a core network. In the uplink, data to be sent tothe base station 1504 from the wireless device 1502 may be provided tothe processing system 1518 of the wireless device 1502. The processingsystem 1508 and the processing system 1518 may implement layer 3 andlayer 2 OSI functionality to process the data for transmission. Layer 2may include an SDAP layer, a PDCP layer, an RLC layer, and a MAC layer,for example, with respect to FIG. 2A, FIG. 2B, FIG. 3 , and FIG. 4A.Layer 3 may include an RRC layer as with respect to FIG. 2B.

After being processed by processing system 1508, the data to be sent tothe wireless device 1502 may be provided to a transmission processingsystem 1510 of base station 1504. Similarly, after being processed bythe processing system 1518, the data to be sent to base station 1504 maybe provided to a transmission processing system 1520 of the wirelessdevice 1502. The transmission processing system 1510 and thetransmission processing system 1520 may implement layer 1 OSIfunctionality. Layer 1 may include a PHY layer with respect to FIG. 2A,FIG. 2B, FIG. 3 , and FIG. 4A. For transmit processing, the PHY layermay perform, for example, forward error correction coding of transportchannels, interleaving, rate matching, mapping of transport channels tophysical channels, modulation of physical channel, multiple-inputmultiple-output (MIMO) or multi-antenna processing, and/or the like.

At the base station 1504, a reception processing system 1512 may receivethe uplink transmission from the wireless device 1502. At the wirelessdevice 1502, a reception processing system 1522 may receive the downlinktransmission from base station 1504. The reception processing system1512 and the reception processing system 1522 may implement layer 1 OSIfunctionality. Layer 1 may include a PHY layer with respect to FIG. 2A,FIG. 2B, FIG. 3 , and FIG. 4A. For receive processing, the PHY layer mayperform, for example, error detection, forward error correctiondecoding, deinterleaving, demapping of transport channels to physicalchannels, demodulation of physical channels, MIMO or multi-antennaprocessing, and/or the like.

As shown in FIG. 15 , a wireless device 1502 and the base station 1504may include multiple antennas. The multiple antennas may be used toperform one or more MIMO or multi-antenna techniques, such as spatialmultiplexing (e.g., single-user MIMO or multi-user MIMO),transmit/receive diversity, and/or beamforming. In other examples, thewireless device 1502 and/or the base station 1504 may have a singleantenna.

The processing system 1508 and the processing system 1518 may beassociated with a memory 1514 and a memory 1524, respectively. Memory1514 and memory 1524 (e.g., one or more non-transitory computer readablemediums) may store computer program instructions or code that may beexecuted by the processing system 1508 and/or the processing system 1518to carry out one or more of the functionalities discussed in the presentapplication. Although not shown in FIG. 15 , the transmission processingsystem 1510, the transmission processing system 1520, the receptionprocessing system 1512, and/or the reception processing system 1522 maybe coupled to a memory (e.g., one or more non-transitory computerreadable mediums) storing computer program instructions or code that maybe executed to carry out one or more of their respectivefunctionalities.

The processing system 1508 and/or the processing system 1518 maycomprise one or more controllers and/or one or more processors. The oneor more controllers and/or one or more processors may comprise, forexample, a general-purpose processor, a digital signal processor (DSP),a microcontroller, an application specific integrated circuit (ASIC), afield programmable gate array (FPGA) and/or other programmable logicdevice, discrete gate and/or transistor logic, discrete hardwarecomponents, an on-board unit, or any combination thereof. The processingsystem 1508 and/or the processing system 1518 may perform at least oneof signal coding/processing, data processing, power control,input/output processing, and/or any other functionality that may enablethe wireless device 1502 and the base station 1504 to operate in awireless environment.

The processing system 1508 and/or the processing system 1518 may beconnected to one or more peripherals 1516 and one or more peripherals1526, respectively. The one or more peripherals 1516 and the one or moreperipherals 1526 may include software and/or hardware that providefeatures and/or functionalities, for example, a speaker, a microphone, akeypad, a display, a touchpad, a power source, a satellite transceiver,a universal serial bus (USB) port, a hands-free headset, a frequencymodulated (FM) radio unit, a media player, an Internet browser, anelectronic control unit (e.g., for a motor vehicle), and/or one or moresensors (e.g., an accelerometer, a gyroscope, a temperature sensor, aradar sensor, a lidar sensor, an ultrasonic sensor, a light sensor, acamera, and/or the like). The processing system 1508 and/or theprocessing system 1518 may receive user input data from and/or provideuser output data to the one or more peripherals 1516 and/or the one ormore peripherals 1526. The processing system 1518 in the wireless device1502 may receive power from a power source and/or may be configured todistribute the power to the other components in the wireless device1502. The power source may comprise one or more sources of power, forexample, a battery, a solar cell, a fuel cell, or any combinationthereof. The processing system 1508 and/or the processing system 1518may be connected to a GPS chipset 1517 and a GPS chipset 1527,respectively. The GPS chipset 1517 and the GPS chipset 1527 may beconfigured to provide geographic location information of the wirelessdevice 1502 and the base station 1504, respectively.

FIG. 16A illustrates an example structure for uplink transmission. Abaseband signal representing a physical uplink shared channel mayperform one or more functions. The one or more functions may comprise atleast one of: scrambling; modulation of scrambled bits to generatecomplex-valued symbols; mapping of the complex-valued modulation symbolsonto one or several transmission layers; transform precoding to generatecomplex-valued symbols; precoding of the complex-valued symbols; mappingof precoded complex-valued symbols to resource elements; generation ofcomplex-valued time-domain Single Carrier-Frequency Division MultipleAccess (SC-FDMA) or CP-OFDM signal for an antenna port; and/or the like.In an example, when transform precoding is enabled, a SC-FDMA signal foruplink transmission may be generated. In an example, when transformprecoding is not enabled, an CP-OFDM signal for uplink transmission maybe generated by FIG. 16A. These functions are illustrated as examplesand it is anticipated that other mechanisms may be implemented invarious embodiments.

FIG. 16B illustrates an example structure for modulation andup-conversion of a baseband signal to a carrier frequency. The basebandsignal may be a complex-valued SC-FDMA or CP-OFDM baseband signal for anantenna port and/or a complex-valued Physical Random Access Channel(PRACH) baseband signal. Filtering may be employed prior totransmission.

FIG. 16C illustrates an example structure for downlink transmissions. Abaseband signal representing a physical downlink channel may perform oneor more functions. The one or more functions may comprise: scrambling ofcoded bits in a codeword to be transmitted on a physical channel;modulation of scrambled bits to generate complex-valued modulationsymbols; mapping of the complex-valued modulation symbols onto one orseveral transmission layers; precoding of the complex-valued modulationsymbols on a layer for transmission on the antenna ports; mapping ofcomplex-valued modulation symbols for an antenna port to resourceelements; generation of complex-valued time-domain OFDM signal for anantenna port; and/or the like. These functions are illustrated asexamples and it is anticipated that other mechanisms may be implementedin various embodiments.

FIG. 16D illustrates another example structure for modulation andup-conversion of a baseband signal to a carrier frequency. The basebandsignal may be a complex-valued OFDM baseband signal for an antenna port.Filtering may be employed prior to transmission.

A wireless device may receive from a base station one or more messages(e.g. RRC messages) comprising configuration parameters of a pluralityof cells (e.g. primary cell, secondary cell). The wireless device maycommunicate with at least one base station (e.g. two or more basestations in dual-connectivity) via the plurality of cells. The one ormore messages (e.g. as a part of the configuration parameters) maycomprise parameters of physical, MAC, RLC, PCDP, SDAP, RRC layers forconfiguring the wireless device. For example, the configurationparameters may comprise parameters for configuring physical and MAClayer channels, bearers, etc. For example, the configuration parametersmay comprise parameters indicating values of timers for physical, MAC,RLC, PCDP, SDAP, RRC layers, and/or communication channels.

A timer may begin running once it is started and continue running untilit is stopped or until it expires. A timer may be started if it is notrunning or restarted if it is running. A timer may be associated with avalue (e.g. the timer may be started or restarted from a value or may bestarted from zero and expire once it reaches the value). The duration ofa timer may not be updated until the timer is stopped or expires (e.g.,due to BWP switching). A timer may be used to measure a timeperiod/window for a process. When the specification refers to animplementation and procedure related to one or more timers, it will beunderstood that there are multiple ways to implement the one or moretimers. For example, it will be understood that one or more of themultiple ways to implement a timer may be used to measure a timeperiod/window for the procedure. For example, a random access responsewindow timer may be used for measuring a window of time for receiving arandom access response. In an example, instead of starting and expiry ofa random access response window timer, the time difference between twotime stamps may be used. When a timer is restarted, a process formeasurement of time window may be restarted. Other exampleimplementations may be provided to restart a measurement of a timewindow.

A device to device (D2D) communication may comprise a Uu interfaceand/or a PC5 interface. In an example, a wireless device may be avehicle. In an example, the D2D communication may be a vehicle tovehicle (V2V) communication. The Uu interface may be a radio interfacebetween a wireless device and a base station. The base station maycommunicate with a wireless device via a Uu link with the Uu interface.The PC5 interface may be a radio interface between a first wirelessdevice and a second wireless device. The first wireless device maycommunicate with the second wireless device via a sidelink with the PC5interface. Both the first wireless device and the second wireless devicemay be within a coverage of the base station. The base station maycommunicate with the first wireless device via a first Uu link with theUu interface. The base station may communicate with the second wirelessdevice via a second Uu link with the Uu interface. In an example, thefirst wireless device may be within a first coverage of a first basestation. The second wireless device may be within a second coverage of asecond base station. The first base station may communicate with thefirst wireless device via a first Uu link with the Uu interface. Thesecond base station may communicate with the second wireless device viaa second Uu link with the Uu interface. In an example, the firstwireless may be within a coverage of the base station. A second wirelessdevice may be out of the coverage of the base station. The firstwireless device may communicate with the second wireless device via asidelink with the PC5 interface. The base station may communicate withthe first wireless device via a Uu link with the Uu interface. In anexample, both the first wireless device and the second wireless devicemay be out of the coverage of the base station. The base station may notbe able to communicate with the first wireless device and the secondwireless device via a Uu link with the Uu interface. The first wirelessdevice may communicate with the second wireless device via a sidelinkwith the PC5 interface.

FIG. 17 illustrates an example of groupcast transmission of vehicle tovehicle (V2V) communication. A transmitter (Tx) wireless device (e.g.,Tx UE1) may communicate with one or more receiver (Rx) wireless devices(e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, Rx UE6, Rx UE7) ingroupcast communication (or multicast communication). The wirelessdevice may be a vehicle. In an example, the Tx wireless device (e.g., TxUE1) may transmit a sidelink transmission (or a sidelink transport block(TB)) to multiple Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, RxUE4, Rx UE5, Rx UE6, Rx UE7) in groupcast communication. In an example,the Tx wireless device (e.g., Tx UE1) may transmit a sidelinktransmission (or a sidelink transport block (TB)) to one of the multipleRx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, RxUE6, Rx UE7) in a multicast communication. The Tx wireless device (e.g.,Tx UE1) and the multiple Rx wireless devices (e.g., Rx UE1, Rx UE2, RxUE3, Rx UE4, Rx UE5, Rx UE6, Rx UE7) may be in a coverage of a basestation. The base station may communicate with the Tx wireless device(e.g., Tx UE1) and the multiple Rx wireless devices (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, Rx UE6, Rx UE7) via one or more Uu linkswith the Uu interface. The Tx wireless device (e.g., Tx UE1) may receiveone or more sidelink acknowledge (ACK/NACK) feedbacks from the multipleRx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, RxUE6, Rx UE7) in response to the transmitting the sidelink transmission(or the sidelink transport block (TB)). In an example, the Tx wirelessdevice (e.g., Tx UE1) may transmit an uplink message to the base stationfor requesting radio resources for one or more sidelink transmissionsbefore transmitting the one or more sidelink transmissions to one ormore Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5,Rx UE6, Rx UE7). The uplink message may comprise an RRC message. In anexample, the uplink message may comprise frequency information oftransmitting and/or receiving sidelink data interested in by the Txwireless device. In an example, the Tx wireless device (e.g., Tx UE1)may transmit an uplink signal to the base station for requesting radioresources for the one or more sidelink transmissions before transmittingthe one or more sidelink transmissions to the one or more Rx wirelessdevices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, Rx UE6, Rx UE7).The uplink signal may comprise a scheduling request (SR). In an example,the Tx wireless device (e.g., Tx UE1) may transmit a MAC CE to the basestation for requesting radio resources for the one or more sidelinktransmissions before transmitting the one or more sidelink transmissionsto the one or more Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, RxUE4, Rx UE5, Rx UE6, Rx UE7). The MAC CE may comprise a MAC CE of abuffer status report (BSR). The Tx wireless device (e.g., Tx UE1) mayreceive a downlink control information from the base station forcontrolling the one or more sidelink transmissions. In an example, theTx wireless device may not be able to communicate with the base station(e.g., for the uplink message, and the downlink control information)when the Tx wireless device is out of the coverage of the base station.

FIG. 18 illustrates an example of groupcast transmission of V2Vcommunication. A Tx wireless device (e.g., Tx UE1) and multiple Rxwireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, Rx UE6,Rx UE7) may be geographically positioned in different locations within ageographical area (or within a zone or multiple adjacent zones). For areliable communication, the Tx wireless device (e.g., Tx UE1) mayperform a sidelink transmission with one or more Rx wireless deviceswithin a desired communication range (DCR). The DCR may be an areadefined by a distance from the Tx wireless device (e.g., within a circlewith a radius R from the Tx wireless device). An Rx wireless devicewithin the DCR may be referred to as an expected Rx wireless device fora HARQ feedback (e.g., Rx UE1, Rx UE6, and Rx UE7). The Tx wirelessdevice (e.g., Tx UE1) may expect a HARQ feedback (ACK/NACK) from theexpected Rx wireless devices (e.g., Rx UE1, Rx UE6, or Rx UE7) inresponse to transmitting a transport block (TB) via a sidelinktransmission with a groupcast communication. An Rx wireless device beingoutside the DCR may be referred to as an unexpected Rx wireless device(e.g., Rx UE2, Rx UE3, Rx UE4, and Rx UE5). The Tx wireless device(e.g., Tx UE1) may not expect a HARQ feedback (ACK/NACK) from theunexpected Rx wireless device (e.g., Rx UE2, Rx UE3, Rx UE4, and Rx UE5)in response to transmitting the TB via the sidelink transmission in thegroupcast communication. A HARQ feedback from the Rx wireless device tothe Tx wireless device may be an ACK or a NACK indication indicating areception status for the TB of the sidelink transmission in the Rxwireless device.

In existing technologies, the multiple Rx wireless devices (e.g., RxUE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, Rx UE6, Rx UE7) receiving thesidelink transmission from the Tx wireless device (e.g., Tx UE1) maydetermine, based on a communication range indication and a geographicallocation of the Tx wireless device, whether to transmit a HARQ feedbackto the Tx wireless device. In an example, the Tx wireless device (e.g.,Tx UE1) may transmit a sidelink control information (SCI) indicating thecommunication range indication and the geographical location of the Txwireless device (e.g., Tx UE1) to the multiple Rx wireless devices(e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, Rx UE6, Rx UE7). Each Rxwireless device of the multiple Rx wireless devices (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, Rx UE6, Rx UE7) may determine, based on theSCI indication and the Rx wireless device’s geographical location,whether a distance between the Tx wireless device and the Rx wirelessdevice is greater than a value of the communication range indication.The Rx wireless device may transmit the HARQ feedback (or anacknowledge) to the Tx wireless device in response to the distance beingequal to or less than the value of the communication range indication.The Rx wireless device may not transmit the HARQ feedback (or theacknowledge) to the Tx wireless device in response to the distance beinggreater than the value of the communication range indication.

The DCR-based HARQ feedback scheme may increase the signaling overheadof the sidelink control channel (SCI) because of the communication rangeindication and the geographical location indication of the Tx wirelessdevice contained in the SCI. In an example, when the geographicallocation of the Tx wireless device is a global unique geographicallocation, the geographical location indication may have more signalingoverhead for the sidelink control channel. The DCR-based HARQ feedbackscheme may require the Rx wireless device to accurately estimate thegeographical location of the Rx wireless device. The geographicallocation of the Rx wireless device may be difficult to estimate in somescenarios (e.g., in an indoor environment, or in a condition of locationestimation with high interference).

In an existing technology, the Rx wireless device may estimate thedistance between the Rx wireless device and the Tx wireless device basedon a reference signal received power (RSRP) measurement. The Tx wirelessdevice (or a base station) may transmit one or more messages comprisinga plurality of configuration parameters to the multiple Rx wirelessdevices. The plurality of configuration parameters may comprise a RSRPthreshold value. Each of the multiple Rx wireless devices may perform ameasurement of an RSRP value of the Tx wireless device. Each Rx wirelessdevice of the multiple Rx wireless devices (e.g., Rx UE1, Rx UE2, RxUE3, Rx UE4, Rx UE5, Rx UE6, Rx UE7) may determine, based on the RSRPmeasurement, whether the RSRP value is greater than the RSRP thresholdvalue or not. The Rx wireless device may transmit the HARQ feedback tothe Tx wireless device in response to the RSRP value being equal to orgreater than the RSRP threshold value. The Rx wireless device may nottransmit the HARQ feedback to the Tx wireless device in response to theRSRP value being less than the RSRP threshold value.

The RSRP measurement based HARQ feedback scheme may have a betterperformance in a line of sight (LOS) condition. When a transmission of areference signal is blocked (e.g., by a building, or a moving train) inhigh frequency, the Rx wireless device, by using the RSRP measurementbased HARQ feedback, may not determine the actual distance between theRx wireless device and the Tx wireless device base on the RSRP value.The reference signal blocking may impact the practical deployment of thesidelink communication system. Implementation of existing technologywith the RSRP measurement may not provide a reliable HARQ feedback whenradio link quality of sidelink is low (e.g., pathloss is greater than athreshold, CQI/RSRP is below a threshold, and/or the like). For example,radio link between the Tx wireless device and the Rx wireless device maybe blocked by an object (e.g., a building). Implementation of existingtechnology with the geographical location measurement may not provide areliable HARQ feedback when the geographical location estimation is notaccurate in some scenarios (e.g., indoor environment, or with highinterference).

There is a need to implement a HARQ feedback mechanism when groupcast orunicast communications are implemented in a sidelink communication.Example embodiments describes an enhanced HARQ feedback based onimproving control information indication in the sidelink and Uuinterface. For example, new configuration parameters in an RRC messageis described to improve signaling efficiency for HARQ transmissionfeedback. For example, a new sidelink control information indication isimplemented to improve signaling efficiency for HARQ transmissionfeedback. Example embodiments disclose several implementations toimprove the HARQ feedback transmission reliability and decrease thesignaling overhead of HARQ feedback for the sidelink communicationsystem with a groupcast (or a unicast) transmission communication. Theseembodiments may enhance/result in high reliability for HARQ feedbackand/or enable HARQ feedback with reduced signaling overhead for thesidelink communication system.

FIG. 19 illustrates an example of groupcast (or unicast) transmissionwith repetition transmissions of V2V communication. A Tx wireless device(e.g., Tx UE1) may communicate with a plurality of Rx wireless devices(e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) with agroupcast communication for a sidelink communication. The Tx wirelessdevice (e.g., Tx UE1) and the plurality of Rx wireless devices (e.g., RxUE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may be in a coverage ofa base station. The base station may transmit one or more radio resourcecontrol (RRC) messages to the Tx wireless device (e.g., Tx UE1). The oneor more RRC messages may comprise configuration parameters for the V2Vcommunication. The configuration parameters may indicate: a plurality ofrepetition values of a physical sidelink shared channel (PSSCH), and arepetition threshold for the PSSCH. Each of the plurality of repetitionvalues of the PSSCH may indicate a number of PSSCH repetitiontransmissions for a transport block (TB) of the sidelink communication.The repetition threshold may be a repetition value for a transmission ofa transport block. A Tx wireless device and/or a Rx wireless device maycontrol/determine whether a HARQ feedback is required based on therepetition threshold. In an example, the Tx wireless device (e.g., TxUE1) may transmit a message to the base station to request radioresources for the sidelink communication. In an example, the message maybe an RRC message. In an example, the message may comprise frequencyinformation of transmitting and/or receiving sidelink data interested inby the Tx wireless device (e.g., Tx UE1). The configuration parametersmay indicate a plurality of radio resources for the Tx wireless device(e.g., Tx UE1). The plurality of radio resources may comprise one ormore radio resource pools. The one or more radio resource pools maycomprise one or more transmission resources pools. The one or more radioresource pools may comprise one or more reception resources pools. In anexample, each resources pool of the one or more transmission resourcepools (or the one or more reception resource pools) may comprise atleast one of: a control region, and a data region. The Tx wirelessdevice (e.g., Tx UE1) may transmit a transport block via the data regionof a transmission resource pool according to control information in thecontrol region of the transmission resource pool. An Rx wireless device(e.g., Rx UE2) of the plurality of Rx wireless devices (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may receive the transport blockvia the data region of a reception resource pool of the Rx wirelessdevice according to control information in a control region of thereception resource pool. In an example, the transmission resource poolof the Tx wireless device (e.g., Tx UE1) may have an associationrelationship with the reception resource pool of the Rx wireless device(e.g., Rx UE2). The association relationship may be a one-to-one mappingrelationship. In an example, the configuration parameters may indicatethe association relationship to the Tx wireless device and/or the Rxwireless device (e.g., Tx UE1 and/or Rx UE2).

The Tx wireless device (e.g., Tx UE1) may transmit one or more RRCmessages to an Rx wireless device of the plurality of Rx wirelessdevices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6). Inan example, the Tx wireless device (e.g., Tx UE1) may transmit the oneor more RRC messages to the Rx wireless device (e.g., Rx UE2) of theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6). The one or more RRC messages may compriseconfiguration parameters of sidelink communication. The configurationparameters of sidelink communication may indicate: a plurality ofrepetition values of a PSSCH, and a repetition threshold for the PSSCH.Each of the plurality of repetition values of the PSSCH may indicate anumber of PSSCH repetition transmissions for a transport block of thesidelink communication. The repetition threshold may be a repetitionvalue for a transmission of a transport block. A Tx wireless deviceand/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. Theconfiguration parameters may indicate a plurality of radio resources foreach of the plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, RxUE3, Rx UE4, Rx UE5, and Rx UE6). In an example, the configurationparameters may indicate a plurality of radio resources for the Rxwireless devices (e.g., Rx UE2). The plurality of radio resources maycomprise one or more radio resource pools. The one or more radioresource pools may comprise one or more transmission and/or receptionresources pools. In an example, each resources pool of the one or moretransmission and/or reception resource pools may comprise at least oneof: a control region, and a data region. The Tx wireless device (e.g.,Tx UE1) may transmit a transport block via the data region of atransmission resource pool of the Tx wireless device according tocontrol information in a control region of the transmission resourcepool. An Rx wireless device (e.g., Rx UE2) of the plurality of Rxwireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and RxUE6) may detect the transport block via a data region of a receptionresource pool of the Rx wireless device according to control informationin a control region of the reception resource pool. The controlinformation in the control region of the reception resource pool mayschedule the transport block of the data region of the receptionresource pool. In an example, the transmission resource pool of the Txwireless device (e.g., Tx UE1) may have an association relationship withthe reception resource pool of the Rx wireless device (e.g., Rx UE2). Inan example, the configuration parameters of sidelink communication mayindicate the association relationship to the Rx wireless device (e.g.,Rx UE2). In an example, the configuration parameters of sidelinkcommunication may indicate the association relationship between thetransmission resource pool of the Tx wireless device (e.g., Tx UE1) anda reception resource pool of an Rx wireless device of the plurality ofRx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, andRx UE6) to the Rx wireless device. In an example, the associationrelationship may be a one-to-one mapping relationship. The Rx wirelessdevice may detect the transport block transmitted by the Tx wirelessdevice according to the association relationship between thetransmission resource pool of the Tx wireless device (e.g., Tx UE1) andthe reception resource pool of the Rx wireless device (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, or Rx UE6).

In an example, the base station may transmit one or more RRC messages toan Rx wireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, orRx UE6) of the plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2,Rx UE3, Rx UE4, Rx UE5, and Rx UE6). The one or more RRC messages maycomprise configuration parameters. The configuration parameters mayindicate: a plurality of repetition values of a PSSCH, and a repetitionthreshold for the PSSCH. Each of the plurality of repetition values ofthe PSSCH may indicate a number of PSSCH repetition transmissions for atransport block of the sidelink communication. The repetition thresholdmay be a repetition value for a transmission of a transport block. A Txwireless device and/or a Rx wireless device may control/determinewhether a HARQ feedback is required based on the repetition threshold.In an example, the Tx wireless device (e.g., Tx UE1) may transmit amessage to the base station to request radio resources for the sidelinkcommunication. In an example, the message may be an RRC message. In anexample, the message may comprise frequency information of transmittingand/or receiving sidelink data interested in by the Tx wireless device.The configuration parameters may indicate a plurality of radio resourcesfor the Rx wireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, RxUE5, or Rx UE6). The plurality of radio resources may comprise one ormore radio resource pools. The one or more radio resource pools maycomprise one or more transmission and/or reception resources pools. Inan example, each resources pool of the one or moretransmission/reception resource pools may comprise at least one of: acontrol region, and a data region. The Rx wireless device (e.g., Rx UE1,Rx UE2, Rx UE3, Rx UE4, Rx UE5, or Rx UE6) may receive a transport blockvia the data region of a reception resource pool according to controlinformation in the control region of the reception resource pool. The Txwireless device (e.g., Tx UE1) may transmit the transport block via adata region of a transmission resource pool of the Tx wireless deviceaccording to control information in a control region of the transmissionresource pool. In an example, the data region may comprise a PSSCH. Thecontrol region may comprise a PSCCH. In an example, the transmissionresource pool of the Tx wireless device (e.g., Tx UE1) may have anassociation relationship with the reception resource pool of the Rxwireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, or RxUE6). The association relationship may be a one-to-one mappingrelationship. In an example, the configuration parameters may indicatethe association relationship to the Rx wireless device (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, or Rx UE6).

The Tx wireless device (e.g., Tx UE1) may transmit a transport block,via a PSSCH, to the plurality of Rx wireless devices (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) in a groupcast communication.The Tx wireless device (e.g., Tx UE1) may transmit the transport blockwith a number of repetition transmissions to the plurality of Rxwireless devices in a groupcast communication. The Tx wireless device(e.g., Tx UE1) may transmit a physical sidelink control channel (PSCCH)comprising a sidelink control information (SCI) scheduling the transportblock to the plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, RxUE3, Rx UE4, Rx UE5, and Rx UE6). The SCI may indicate the number of therepetition transmissions. In an example, the number of the repetitiontransmissions may be one of the plurality of repetition values of thePSSCH (e.g., indicated by the one or more RRC messages). The number ofthe repetition transmissions may comprise transmission andretransmissions of the transport block. A Rx wireless device (e.g., RxUE2) may receive, from the Tx wireless device (e.g., Tx UE1), the SCIindicating one of the plurality of repetition values of the PSSCH. TheRx wireless device (e.g., Rx UE2) may determine, based on the repetitionthreshold and the one of the plurality of repetition values, whether totransmit a positive/negative acknowledgment (ACK/NACK) for the transportblock scheduled by the SCI. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the repetition threshold and the one of theplurality of repetition values, to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI. In anexample, the Rx wireless device (e.g., Rx UE2) may determine to transmita positive/negative acknowledgment for the transport block scheduled bythe SCI in response to the one of the plurality of repetition valuesbeing equal to the repetition threshold. In an example, the Rx wirelessdevice (e.g., Rx UE2) may determine to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI in responseto the one of the plurality of repetition values being less than therepetition threshold. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the repetition threshold and the one of theplurality of repetition values, not to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI. In anexample, the Rx wireless device (e.g., Rx UE2) may determine not totransmit a positive/negative acknowledgment for the transport blockscheduled by the SCI in response to the one of the plurality ofrepetition values being greater than the repetition threshold. The Rxwireless device (e.g., Rx UE2) may detect the transport block scheduledby the SCI. Base on the detecting the transport block, the Rx wirelessdevice (e.g., Rx UE2) may transmit the positive/negative acknowledgmentto the Tx wireless device (e.g., Tx UE1) in response to the Rx wirelessdevice determining to transmit the positive/negative acknowledgment forthe transport block. The Rx wireless device (e.g., Rx UE2) may transmitthe positive/negative acknowledgment (e.g., ACK or NACK) to the Txwireless device (e.g., Tx UE1) via a physical sidelink feedback channel(PSFCH) in response to the Rx wireless device determining to transmitthe positive/negative acknowledgment for the transport block. The PSFCHmay comprise an association with the PSSCH used to transmit thetransport block of the Tx wireless device (e.g., Tx UE1). Theconfiguration parameters may indicate the association between the PSSCHand the PSFCH. The Rx wireless device (e.g., Rx UE2) may determine,based on the association, the PSFCH in response to receiving the PSSCH.In an example, the PSFCH may use the same frequency resources as thePSSCH. In an example, the PSFCH may use a portion of frequency resourcesof the PSSCH. In an example, the PSFCH may use frequency resourceswithout overlapping with the PSSCH. In an example, the Rx wirelessdevice (e.g., Rx UE2) may transmit a transport block via the PSFCH inresponse to the Rx wireless device determining not to transmit thepositive/negative acknowledgment for the transport block. Each of theplurality of repetition values of the PSSCH may indicate a plurality ofrepetition transmissions of the PSSCH. The plurality of repetitiontransmissions may comprise transmission and retransmissions of thePSSCH. In an example, the transmission and retransmissions of the PSSCHmay comprise transmission and retransmissions of the PSSCH with a sameor different redundancy versions of channel coding. The Tx wirelessdevice (e.g., Tx UE1) may transmit the PSCCH comprising the SCI to theRx wireless device (e.g., Rx UE2). The SCI may indicate the same ordifferent redundancy versions of channel coding for the plurality ofrepetition transmissions. The Rx wireless device (e.g., Rx UE2) mayreceive the PSCCH comprising the SCI via a reception resource pool. Thereception resource pool may comprise continuous or noncontinuousresources in frequency domain. The reception resource pool may comprisecontinuous or noncontinuous resources in time domain. The receptionresource pool may comprise a reception periodicity in sidelink. The Rxwireless device may receive the reception resource pool according to thereception periodicity in sidelink. In an example, the base station mayconfigure the reception periodicity of the reception resource pool tothe Rx wireless device (e.g., Rx UE2). In an example, the Tx wirelessdevice (e.g., Tx UE1) may configure the reception periodicity of thereception resource pool to the Rx wireless device (e.g., Rx UE2).

In an example, the Tx wireless device (e.g., Tx UE1) may transmit atransport block, via a PSSCH, to an Rx wireless device (e.g., Rx UE2) ina unicast communication. The Tx wireless device (e.g., Tx UE1) maytransmit the transport block with a number of repetition transmissionsto the Rx wireless device (e.g., Rx UE2). The Tx wireless device (e.g.,Tx UE1) may transmit a PSCCH comprising an SCI scheduling the transportblock to the Rx wireless devices (e.g., Rx UE2). The SCI may indicatethe number of the repetition transmissions. In an example, the number ofthe repetition transmissions may be one of the plurality of repetitionvalues of the PSSCH (e.g., indicated by the one or more RRC messages).The number of the repetition transmissions may comprise transmission andretransmissions of the transport block. The Rx wireless device (e.g., RxUE2) may receive, from the Tx wireless device (e.g., Tx UE1), the SCIindicating one of the plurality of repetition values of the PSSCH. TheRx wireless device (e.g., Rx UE2) may determine, based on the repetitionthreshold and the one of the plurality of repetition values, whether totransmit a positive/negative acknowledgment for the transport blockscheduled by the SCI. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the repetition threshold and the one of theplurality of repetition values, to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI. In anexample, the Rx wireless device (e.g., Rx UE2) may determine to transmita positive/negative acknowledgment (ACK/NACK) for the transport blockscheduled by the SCI in response to the one of the plurality ofrepetition values being equal to the repetition threshold. In anexample, the Rx wireless device (e.g., Rx UE2) may determine to transmita positive/negative acknowledgment (ACK/NACK) for the transport blockscheduled by the SCI in response to the one of the plurality ofrepetition values being less than the repetition threshold. The Rxwireless device (e.g., Rx UE2) may determine, based on the repetitionthreshold and the one of the plurality of repetition values, not totransmit a positive/negative acknowledgment (ACK/NACK) for the transportblock scheduled by the SCI. In an example, the Rx wireless device (e.g.,Rx UE2) may determine not to transmit a positive/negative acknowledgment(ACK/NACK) for the transport block scheduled by the SCI in response tothe one of the plurality of repetition values being greater than therepetition threshold. The Rx wireless device (e.g., Rx UE2) may detectthe transport block scheduled by the SCI. Base on the detecting thetransport block, the Rx wireless device (e.g., Rx UE2) may transmit thepositive/negative acknowledgment to the Tx wireless device (e.g., TxUE1) in response to the Rx wireless device (e.g., Rx UE2) determining totransmit the positive/negative acknowledgment for the transport block.Each of the plurality of repetition values of the PSSCH may indicate aplurality of repetition transmissions of the PSSCH. The plurality ofrepetition transmissions may comprise transmission and retransmissionsof the PSSCH. In an example, the transmission and retransmissions of thePSSCH may comprise transmission and retransmissions of the PSSCH with asame or different redundancy versions of channel coding. The Tx wirelessdevice (e.g., Tx UE1) may transmit the PSCCH comprising the SCI to theRx wireless device (e.g., Rx UE2). The SCI may indicate the same ordifferent redundancy versions of channel coding for the plurality ofrepetition transmissions. The Rx wireless device (e.g., Rx UE2) mayreceive the PSCCH comprising the SCI via a reception resource pool. Thereception resource pool may comprise continuous or noncontinuousresources in frequency domain. The reception resource pool may comprisecontinuous or noncontinuous resources in time domain. The receptionresource pool may comprise a reception periodicity in sidelink. The Rxwireless device may receive the reception resource pool according to thereception periodicity in sidelink. In an example, the base station mayconfigure the reception periodicity of the reception resource pool tothe Rx wireless device (e.g., Rx UE2). In an example, the Tx wirelessdevice (e.g., Tx UE1) may configure the reception periodicity of thereception resource pool to the Rx wireless device (e.g., Rx UE2).

In an example, the Tx wireless device (e.g., Tx UE1) may transmit aPSCCH comprising an SCI (e.g., scheduling a transport block) to theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6) in a groupcast communication. The SCI may comprise abit field indicating whether to feedback an acknowledge (e.g., ACK/NACK)for the transport block transmitted by the Tx wireless device (e.g., TxUE1). The bit field may comprise N bits. In an example, N may be aninteger and greater than 0. In an example, the bit field may compriseone bit. In an example, the plurality of Rx wireless devices (e.g., RxUE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may determine not tofeedback the acknowledge for the transport block in response to the bitfield (e.g., comprising one bit) being set to 1 (or 0). The plurality ofRx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, andRx UE6) may determine to feedback the acknowledge for the transportblock in response to the bit field (e.g., comprising one bit) being setto 0 (or 1). The plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2,Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may enhance/result in highreliability for HARQ feedback and/or enable HARQ feedback with reducedsignaling overhead for the sidelink communication system. In an example,the Tx wireless device (e.g., Tx UE1) may transmit a PSCCH comprising anSCI (e.g., scheduling a transport block) to an Rx wireless device (e.g.,Rx UE2) in unicast communication. The SCI may comprise a bit fieldindicating whether to feedback an acknowledge (e.g., ACK/NACK) for thetransport block transmitted by the Tx wireless device (e.g., Tx UE1).The bit field may comprise N bits. In an example, N may be an integerand greater than 0. In an example, the bit field may comprise one bit.In an example, the Rx wireless device (e.g., Rx UE2) may determine notto feedback the acknowledge for the transport block in response to thebit field (e.g., comprising one bit) being set to 1 (or 0). The Rxwireless devices (e.g., Rx UE2) may determine to feedback theacknowledge for the transport block in response to the bit field (e.g.,comprising one bit) being set to 0 (or 1). The Rx wireless devices(e.g., Rx UE2) may enhance/result in high reliability for HARQ feedbackand/or enable HARQ feedback with reduced signaling overhead for thesidelink communication system.

FIG. 20 illustrates an example of a procedure of groupcast (or unicast)transmission with repetition transmissions of V2V communication. A Txwireless device (e.g., Tx UE1) may receive one or more RRC messages froma base station at time T1. The one or more RRC messages may compriseconfiguration parameters. The configuration parameters may indicate: aplurality of repetition values of a PSSCH, and a repetition thresholdfor the PSSCH. Each of the plurality of repetition values of the PSSCHmay indicate a number of PSSCH repetition transmissions for a transportblock of the sidelink communication. The repetition threshold may be arepetition value for a transmission of a transport block. A Tx wirelessdevice and/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. The Rx wirelessdevice (e.g., Rx UE2) may receive one or more RRC messages from the Txwireless device (Tx UE1) at time T2. The one or more RRC messages maycomprise configuration parameters of sidelink communication. Theconfiguration parameters of sidelink communication may indicate: aplurality of repetition values of a PSSCH, and a repetition thresholdfor the PSSCH. Each of the plurality of repetition values of the PSSCHmay indicate a number of PSSCH repetition transmissions for a transportblock of the sidelink communication. The repetition threshold may be arepetition value for a transmission of a transport block. In an example,the Rx wireless device (e.g., Rx UE2) may receive one or more RRCmessages from the base station at time T2. The one or more RRC messagesmay comprise configuration parameters of sidelink communication. Theconfiguration parameters of sidelink communication may indicate: aplurality of repetition values of a PSSCH, and a repetition thresholdfor the PSSCH. Each of the plurality of repetition values of the PSSCHmay indicate a number of PSSCH repetition transmissions for a transportblock of the sidelink communication. The repetition threshold may be arepetition value for a transmission of a transport block. In an example,the configuration parameters may indicate a plurality of radio resourcesfor the Tx wireless device (e.g., Tx UE1). The plurality of radioresources may comprise one or more radio resource pools. The one or moreradio resource pools may comprise one or more transmission resourcespools. The one or more radio resource pools may comprise one or morereception resources pools. In an example, each resources pool of the oneor more transmission resource pools (or the one or more receptionresource pools) may comprise at least one of: a control region, and adata region. The Tx wireless device (e.g., Tx UE1) may transmit atransport block via the data region of a transmission resource poolaccording to control information in the control region of thetransmission resource pool. The Rx wireless device (e.g., Rx UE2) of theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6) may receive the transport block via the data regionof a reception resource pool of the Rx wireless device according tocontrol information in a control region of the reception resource pool.In an example, the transmission resource pool of the Tx wireless device(e.g., Tx UE1) may have an association relationship with the receptionresource pool of the Rx wireless device (e.g., Rx UE2). The associationrelationship may be a one-to-one mapping relationship. In an example,the configuration parameters may indicate the association relationshipto the Tx wireless device and/or the Rx wireless device (e.g., Tx UE1and/or Rx UE2).

The Rx wireless device (e.g., Rx UE2) may receive a PSCCH comprising asidelink control information (SCI) at time T3. The SCI may indicate oneof the plurality of repetition values of the PSSCH. The SCI may schedulea transport block with a number of repetition transmissions. The numberof repetition transmissions may be the one of the plurality ofrepetition values of the PSSCH. The Rx wireless device (e.g., Rx UE2)may determine, based on the repetition threshold and the one of theplurality of repetition values, whether to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI. The Rxwireless device (e.g., Rx UE2) may determine, based on the repetitionthreshold and the one of the plurality of repetition values, to transmita positive/negative acknowledgment for the transport block scheduled bythe SCI at time T4. In an example, the Rx wireless device (e.g., Rx UE2)may determine to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of theplurality of repetition values being equal to the repetition threshold.In an example, the Rx wireless device (e.g., Rx UE2) may determine totransmit a positive/negative acknowledgment for the transport blockscheduled by the SCI in response to the one of the plurality ofrepetition values being less than the repetition threshold. The Rxwireless device (e.g., Rx UE2) may determine, based on the repetitionthreshold and the one of the plurality of repetition values, not totransmit a positive/negative acknowledgment for the transport blockscheduled by the SCI. In an example, the Rx wireless device (e.g., RxUE2) may determine not to transmit a positive/negative acknowledgmentfor the transport block scheduled by the SCI in response to the one ofthe plurality of repetition values being greater than the repetitionthreshold. The Rx wireless device (e.g., Rx UE2) may detect thetransport block scheduled by the SCI at time T5. The Rx wireless device(e.g., Rx UE2) may transmit acknowledgement (ACK)/negativeacknowledgement (NACK) to the Tx wireless device (e.g., Tx UE1) inresponse to the Rx wireless device determining to transmit thepositive/negative acknowledgment at time T6. In an example, the Txwireless device (e.g., Tx UE1) may transmit a PSCCH comprising an SCI tothe plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, RxUE4, Rx UE5, and Rx UE6). The SCI may comprise a bit field indicatingwhether to feedback an acknowledge (e.g., ACK/NACK) for a transportblock transmitted by the Tx wireless device (e.g., Tx UE1). The bitfield may comprise N bits. In an example, N may be an integer andgreater than 0. In an example, the bit field may comprise one bit. In anexample, the plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, RxUE3, Rx UE4, Rx UE5, and Rx UE6) may determine not to feedback theacknowledge for the transport block in response to the bit field (e.g.,comprising one bit) being set to 1 (or 0). In an example, the pluralityof Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5,and Rx UE6) may determine to feedback the acknowledge for the transportblock in response to the bit field (e.g., comprising one bit) being setto 0 (or 1).

FIG. 21 illustrates an example of a flow chart of groupcast (or unicast)transmission with repetition transmissions of V2V communication. An Rxwireless device (e.g., Rx UE2) may receive one or more RRC messages froma Tx wireless device (Tx UE1). The one or more RRC messages may compriseconfiguration parameters of sidelink communication. The configurationparameters of sidelink communication may indicate: a plurality ofrepetition values of a PSSCH, and a repetition threshold for the PSSCH.Each of the plurality of repetition values of the PSSCH may indicate anumber of PSSCH repetition transmissions for a transport block of thesidelink communication. The repetition threshold may be a repetitionvalue for a transmission of a transport block. A Tx wireless deviceand/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. In an example,the Rx wireless device (e.g., Rx UE2) may receive one or more RRCmessages from a base station. The one or more RRC messages may compriseconfiguration parameters of sidelink communication. The configurationparameters of sidelink communication may indicate: a plurality ofrepetition values of a PSSCH, and a repetition threshold for the PSSCH.Each of the plurality of repetition values of the PSSCH may indicate anumber of PSSCH repetition transmissions for a transport block of thesidelink communication. The repetition threshold may be a repetitionvalue for a transmission of a transport block. A Tx wireless deviceand/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. In an example,the configuration parameters may indicate a plurality of radio resourcesfor the Tx wireless device (e.g., Tx UE1). The plurality of radioresources may comprise one or more radio resource pools. The one or moreradio resource pools may comprise one or more transmission resourcespools. The one or more radio resource pools may comprise one or morereception resources pools. In an example, each resources pool of the oneor more transmission resource pools (or the one or more receptionresource pools) may comprise at least one of: a control region, and adata region. The Tx wireless device (e.g., Tx UE1) may transmit atransport block via the data region of a transmission resource pool ofthe Tx wireless device according to control information in the controlregion of the transmission resource pool. The Rx wireless device (e.g.,Rx UE2) of the plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2,Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may receive the transport block viathe data region of a reception resource pool according to controlinformation in a control region of the reception resource pool. In anexample, the transmission resource pool of the Tx wireless device (e.g.,Tx UE1) may have an association relationship with the reception resourcepool of the Rx wireless device (e.g., Rx UE2). In an example, theconfiguration parameters may indicate the association relationship tothe Tx wireless device and/or the Rx wireless device (e.g., Tx UE1and/or Rx UE2).

The Rx wireless device (e.g., Rx UE2) may receive a PSCCH comprising asidelink control information (SCI). The SCI may indicate one of theplurality of repetition values of the PSSCH. The SCI may schedule atransport block with a number of repetition transmissions. The number ofrepetition transmissions may be the one of the plurality of repetitionvalues of the PSSCH. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the repetition threshold and the one of theplurality of repetition values, whether to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI. The Rxwireless device (e.g., Rx UE2) may determine, based on the repetitionthreshold and the one of the plurality of repetition values, to transmita positive/negative acknowledgment for the transport block scheduled bythe SCI. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of theplurality of repetition values being equal to the repetition threshold.In an example, the Rx wireless device (e.g., Rx UE2) may determine totransmit a positive/negative acknowledgment for the transport blockscheduled by the SCI in response to the one of the plurality ofrepetition values being less than the repetition threshold. The Rxwireless device (e.g., Rx UE2) may determine, based on the repetitionthreshold and the one of the plurality of repetition values, not totransmit a positive/negative acknowledgment for the transport blockscheduled by the SCI. In an example, the Rx wireless device (e.g., RxUE2) may determine not to transmit a positive/negative acknowledgmentfor the transport block scheduled by the SCI in response to the one ofthe plurality of repetition values being greater than the repetitionthreshold. The Rx wireless device (e.g., Rx UE2) may detect or receivethe transport block scheduled by the SCI. The Rx wireless device (e.g.,Rx UE2) may transmit, via a transmission resource pool, acknowledgement(ACK)/ negative acknowledgement (NACK) to the Tx wireless device (e.g.,Tx UE1) in response to the Rx wireless device determining to transmitthe positive/negative acknowledgment.

A wireless device may receive one or more messages comprisingconfiguration parameters indicating: a plurality of repetition values ofa physical sidelink shared channel (PSSCH), and a repetition thresholdfor the PSSCH. The wireless device may receive a sidelink controlinformation indicating one of the plurality of repetition values. Thewireless device may determine, based on the repetition threshold and theone of the plurality of repetition values, to transmit anpositive/negative acknowledgment for a transport block scheduled by thesidelink control information. The wireless device may detect/receive thetransport block scheduled by the sidelink control information. Thewireless device may transmit the positive/negative acknowledgment forthe transport block in response to the determining to transmit thepositive/negative acknowledgment. Each of the plurality of repetitionvalues of the PSSCH may indicate a plurality of repetition transmissionsof the PSSCH. The plurality of repetition transmissions may comprisetransmission and retransmissions of the PSSCH. The transmission andretransmissions of the PSSCH may comprise transmission andretransmissions of the PSSCH with different redundancy versions. Thedifferent redundancy versions may be indicated to the wireless devicevia a sidelink control information. The different redundancy versionsmay be indicated to the wireless device via a physical downlink controlchannel. The repetition threshold for the PSSCH may be a repetitionvalue for a transmission. The receiving the sidelink control informationmay comprise receiving the sidelink control information from a receptionresource pool. The reception resource pool may comprise continuous ornoncontinuous resources in frequency domain. The reception resource poolmay comprise continuous or noncontinuous resources in time domain. Thereception resource pool may comprise a reception periodicity in asidelink. The reception periodicity may be configured by a basedstation. The reception periodicity may be configured by a wirelessdevice. The determination, based on the repetition threshold and the oneof the plurality of repetition values, of transmitting thepositive/negative acknowledgment may comprise determining to transmitthe positive/negative acknowledgment in response to the one of theplurality of repetition values being less than the repetition threshold.The determination, based on the repetition threshold and the one of theplurality of repetition values, of transmitting the positive/negativeacknowledgment may comprise determining to transmit thepositive/negative acknowledgment in response to the one of the pluralityof repetition values being equal to the repetition threshold. Thewireless device may determine not to transmit the positive/negativeacknowledgment in response to the one of the plurality of repetitionvalues being greater than the repetition threshold. The detection of thetransport block scheduled by the sidelink control information maycomprise detecting the transport block transmitted via a sidelink. Thereception of the one or more messages may comprise receiving, by thewireless device, the one or more messages from a first wireless device.The first wireless device may comprise a wireless device performingsidelink communication with the wireless device. The reception of theone or more messages may comprise receiving, by the wireless device, theone or more messages from a base station. The base station may comprisea coverage covering at least one of the first wireless device and thewireless device.

FIG. 22 illustrates an example of groupcast (or unicast) transmissionwith repetition transmissions of V2V communication. A Tx wireless device(e.g., Tx UE1) may communicate with a plurality of Rx wireless devices(e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) with agroupcast communication for a sidelink communication. The Tx wirelessdevice (e.g., Tx UE1) and the plurality of Rx wireless devices (e.g., RxUE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may be in a coverage ofa base station. The base station may transmit one or more radio resourcecontrol (RRC) messages to the Tx wireless device (e.g., Tx UE1). The oneor more RRC messages may comprise configuration parameters for the V2Vcommunication. The configuration parameters may indicate: a plurality ofrepetition values of a physical sidelink shared channel (PSSCH), and arepetition threshold for the PSSCH. Each of the plurality of repetitionvalues of the PSSCH may indicate a number of PSSCH repetitiontransmissions for a transport block of the sidelink communication. Therepetition threshold may be a repetition value for a transmission of atransport block. A Tx wireless device and/or a Rx wireless device maycontrol/determine whether a HARQ feedback is required based on therepetition threshold. In an example, the Tx wireless device (e.g., TxUE1) may transmit a message to the base station to request radioresources for the sidelink communication. In an example, the message maybe an RRC message. In an example, the message may comprise frequencyinformation of transmitting and/or receiving sidelink data interested inby the Tx wireless device (e.g., Tx UE1). The configuration parametersmay indicate a plurality of radio resources for the Tx wireless device(e.g., Tx UE1). The plurality of radio resources may comprise one ormore radio resource pools. The one or more radio resource pools maycomprise one or more transmission resources pools. The one or more radioresource pools may comprise one or more reception resources pools. In anexample, each resources pool of the one or more transmission resourcepools (or the one or more reception resource pools) may comprise atleast one of: a control region, and a data region. The Tx wirelessdevice (e.g., Tx UE1) may transmit a transport block via the data regionof a transmission resource pool according to control information in thecontrol region of the transmission resource pool. An Rx wireless device(e.g., Rx UE2) of the plurality of Rx wireless devices (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may receive the transport blockvia the data region of a reception resource pool of the Rx wirelessdevice according to control information in a control region of thereception resource pool. In an example, the transmission resource poolof the Tx wireless device (e.g., Tx UE1) may have an associationrelationship with the reception resource pool of the Rx wireless device(e.g., Rx UE2). The association relationship may be a one-to-one mappingrelationship. In an example, the configuration parameters may indicatethe association relationship to the Tx wireless device and/or the Rxwireless device (e.g., Tx UE1 and/or Rx UE2).

The Tx wireless device (e.g., Tx UE1) may transmit one or more RRCmessages to an Rx wireless device of the plurality of Rx wirelessdevices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6). Inan example, the Tx wireless device (e.g., Tx UE1) may transmit the oneor more RRC messages to the Rx wireless device (e.g., Rx UE2) of theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6). The one or more RRC messages may compriseconfiguration parameters of sidelink communication. The configurationparameters of sidelink communication may indicate: a plurality ofrepetition values of a PSSCH, and a repetition threshold for the PSSCH.Each of the plurality of repetition values of the PSSCH may indicate anumber of PSSCH repetition transmissions for a transport block of thesidelink communication. The repetition threshold may be a repetitionvalue for a transmission of a transport block. A Tx wireless deviceand/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. Theconfiguration parameters may indicate a plurality of radio resources foreach of the plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, RxUE3, Rx UE4, Rx UE5, and Rx UE6). In an example, the configurationparameters may indicate a plurality of radio resources for the Rxwireless devices (e.g., Rx UE2). The plurality of radio resources maycomprise one or more radio resource pools. The one or more radioresource pools may comprise one or more transmission and/or receptionresources pools. In an example, each resources pool of the one or moretransmission and/or reception resource pools may comprise at least oneof: a control region, and a data region. The Tx wireless device (e.g.,Tx UE1) may transmit a transport block via the data region of atransmission resource pool of the Tx wireless device according tocontrol information in a control region of the transmission resourcepool. An Rx wireless device (e.g., Rx UE2) of the plurality of Rxwireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and RxUE6) may detect the transport block via a data region of a receptionresource pool of the Rx wireless device according to control informationin a control region of the reception resource pool. The controlinformation in the control region of the reception resource pool mayschedule the transport block of the data region of the receptionresource pool. In an example, the transmission resource pool of the Txwireless device (e.g., Tx UE1) may have an association relationship withthe reception resource pool of the Rx wireless device (e.g., Rx UE2). Inan example, the configuration parameters of sidelink communication mayindicate the association relationship to the Rx wireless device (e.g.,Rx UE2). In an example, the configuration parameters of sidelinkcommunication may indicate the association relationship between thetransmission resource pool of the Tx wireless device (e.g., Tx UE1) anda reception resource pool of an Rx wireless device of the plurality ofRx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, andRx UE6) to the Tx wireless device and/or the Rx wireless device. In anexample, the association relationship may be a one-to-one mappingrelationship. The Rx wireless device may detect the transport blocktransmitted by the Tx wireless device according to the associationrelationship between the transmission resource pool of the Tx wirelessdevice (e.g., Tx UE1) and the reception resource pool of the Rx wirelessdevice (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, or Rx UE6).

In an example, the base station may transmit one or more RRC messages toan Rx wireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, orRx UE6) of the plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2,Rx UE3, Rx UE4, Rx UE5, and Rx UE6). The one or more RRC messages maycomprise configuration parameters. The configuration parameters mayindicate: a plurality of repetition values of a PSSCH, and a repetitionthreshold for the PSSCH. Each of the plurality of repetition values ofthe PSSCH may indicate a number of PSSCH repetition transmissions for atransport block of the sidelink communication. The repetition thresholdmay be a repetition value for a transmission of a transport block. A Txwireless device and/or a Rx wireless device may control/determinewhether a HARQ feedback is required based on the repetition threshold.In an example, the Tx wireless device (e.g., Tx UE1) may transmit amessage to the base station to request radio resources for the sidelinkcommunication. In an example, the message may be an RRC message. In anexample, the message may comprise frequency information of transmittingand/or receiving sidelink data interested in by the Tx wireless device.The configuration parameters may indicate a plurality of radio resourcesfor the Rx wireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, RxUE5, or Rx UE6). The plurality of radio resources may comprise one ormore radio resource pools. The one or more radio resource pools maycomprise one or more transmission and/or reception resources pools. Inan example, each resources pool of the one or moretransmission/reception resource pools may comprise at least one of: acontrol region, and a data region. The Rx wireless device (e.g., Rx UE1,Rx UE2, Rx UE3, Rx UE4, Rx UE5, or Rx UE6) may receive a transport blockvia the data region of a reception resource pool according to controlinformation in the control region of the reception resource pool. The Txwireless device (e.g., Tx UE1) may transmit the transport block via adata region of a transmission resource pool of the Tx wireless deviceaccording to control information in a control region of the transmissionresource pool. In an example, the data region may comprise a PSSCH. Thecontrol region may comprise a PSCCH. In an example, the transmissionresource pool of the Tx wireless device (e.g., Tx UE1) may have anassociation relationship with the reception resource pool of the Rxwireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, or RxUE6). In an example, the configuration parameters may indicate theassociation relationship to the Tx wireless device (e.g., Tx UE1) and/orRx wireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, or RxUE6).

The Tx wireless device (e.g., Tx UE1) may transmit a transport block,via a PSSCH, to the plurality of Rx wireless devices (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) in a groupcast communication.The Tx wireless device (e.g., Tx UE1) may transmit the transport blockwith a number of repetition transmissions to the plurality of Rxwireless devices in a groupcast communication. The Tx wireless device(e.g., Tx UE1) may transmit a media access control element (MAC CE)activating one or more of the plurality of repetition values of thePSSCH to each of the plurality of Rx wireless devices. The Tx wirelessdevice (e.g., Tx UE1) may transmit a physical sidelink control channel(PSCCH) comprising a sidelink control information (SCI) scheduling thetransport block to the plurality of Rx wireless devices (e.g., Rx UE1,Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6). The SCI may indicate thenumber of the repetition transmissions. In an example, the number of therepetition transmissions may be one of the one or more of the pluralityof repetition values of the PSSCH (e.g., indicated by the one or moreRRC messages). The number of the repetition transmissions may comprisetransmission and retransmissions of the transport block. A Rx wirelessdevice (e.g., Rx UE2) may receive, from the Tx wireless device (e.g., TxUE1), the SCI indicating one of the one or more of the plurality ofrepetition values of the PSSCH (e.g., activated by the MAC CE). The Rxwireless device (e.g., Rx UE2) may determine, based on the repetitionthreshold and the one of the one or more of the plurality of repetitionvalues, whether to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI. The Rx wireless device (e.g., RxUE2) may determine, based on the repetition threshold and the one of theone or more of the plurality of repetition values, to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of the oneor more of the plurality of repetition values being equal to therepetition threshold. In an example, the Rx wireless device (e.g., RxUE2) may determine to transmit a positive/negative acknowledgment forthe transport block scheduled by the SCI in response to the one of theone or more of the plurality of repetition values being less than therepetition threshold. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the repetition threshold and the one of the one ormore of the plurality of repetition values, not to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine not to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of the oneor more of the plurality of repetition values being greater than therepetition threshold. The Rx wireless device (e.g., Rx UE2) may detectthe transport block scheduled by the SCI. Base on the detecting thetransport block, the Rx wireless device (e.g., Rx UE2) may transmit thepositive/negative acknowledgment to the Tx wireless device (e.g., TxUE1) in response to the Rx wireless device determining to transmit thepositive/negative acknowledgment for the transport block. The Rxwireless device (e.g., Rx UE2) may transmit the positive/negativeacknowledgment (e.g., ACK or NACK) to the Tx wireless device (e.g., TxUE1) via a physical sidelink feedback channel (PSFCH) in response to theRx wireless device determining to transmit the positive/negativeacknowledgment for the transport block. The PSFCH may comprise anassociation with the PSSCH used to transmit the transport block of theTx wireless device (e.g., Tx UE1). The configuration parameters mayindicate the association between the PSSCH and the PSFCH. The Rxwireless device (e.g., Rx UE2) may determine, based on the association,the PSFCH in response to receiving the PSSCH. In an example, the PSFCHmay use the same frequency resources as the PSSCH. In an example, thePSFCH may use a portion of frequency resources of the PSSCH. In anexample, the PSFCH may use frequency resources without overlapping withthe PSSCH. In an example, the Rx wireless device (e.g., Rx UE2) maytransmit a transport block via the PSFCH in response to the Rx wirelessdevice determining not to transmit the positive/negative acknowledgmentfor the transport block. Each of the plurality of repetition values ofthe PSSCH may indicate a plurality of repetition transmissions of thePSSCH. The plurality of repetition transmissions may comprisetransmission and retransmissions of the PSSCH. In an example, thetransmission and retransmissions of the PSSCH may comprise transmissionand retransmissions of the PSSCH with a same or different redundancyversions of channel coding. The Tx wireless device (e.g., Tx UE1) maytransmit the PSCCH comprising the SCI to the Rx wireless device (e.g.,Rx UE2). The SCI may indicate the same or different redundancy versionsof channel coding for the plurality of repetition transmissions. The Rxwireless device (e.g., Rx UE2) may receive the PSCCH comprising the SCIvia a reception resource pool. The reception resource pool may comprisecontinuous or noncontinuous resources in frequency domain. The receptionresource pool may comprise continuous or noncontinuous resources in timedomain. The reception resource pool may comprise a reception periodicityin sidelink. The Rx wireless device may receive the reception resourcepool according to the reception periodicity in sidelink. In an example,the base station may configure the reception periodicity of thereception resource pool to the Rx wireless device (e.g., Rx UE2). In anexample, the Tx wireless device (e.g., Tx UE1) may configure thereception periodicity of the reception resource pool to the Rx wirelessdevice (e.g., Rx UE2).

In an example, the Tx wireless device (e.g., Tx UE1) may transmit atransport block, via a PSSCH, to an Rx wireless device (e.g., Rx UE2) ina unicast communication. The Tx wireless device (e.g., Tx UE1) maytransmit a MAC CE activating one or more of the plurality of repetitionvalues of the PSSCH to the Rx wireless device (e.g., Rx UE2). The Txwireless device (e.g., Tx UE1) may transmit the transport block with anumber of repetition transmissions to the Rx wireless device (e.g., RxUE2). The Tx wireless device (e.g., Tx UE1) may transmit a PSCCHcomprising an SCI scheduling the transport block to the Rx wirelessdevices (e.g., Rx UE2). The SCI may indicate the number of therepetition transmissions. In an example, the number of the repetitiontransmissions may be one of the one or more of the plurality ofrepetition values of the PSSCH (e.g., activated by the MAC CE). Thenumber of the repetition transmissions may comprise transmission andretransmissions of the transport block. The Rx wireless device (e.g., RxUE2) may receive, from the Tx wireless device (e.g., Tx UE1), the SCIindicating one of the one or more of the plurality of repetition valuesof the PSSCH. The Rx wireless device (e.g., Rx UE2) may determine, basedon the repetition threshold and the one of the one or more of theplurality of repetition values, whether to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI. The Rxwireless device (e.g., Rx UE2) may determine, based on the repetitionthreshold and the one of the one or more of the plurality of repetitionvalues, to transmit a positive/negative acknowledgment for the transportblock scheduled by the SCI. In an example, the Rx wireless device (e.g.,Rx UE2) may determine to transmit a positive/negative acknowledgment forthe transport block scheduled by the SCI in response to the one of theone or more of the plurality of repetition values being equal to therepetition threshold. In an example, the Rx wireless device (e.g., RxUE2) may determine to transmit a positive/negative acknowledgment forthe transport block scheduled by the SCI in response to the one of theone or more of the plurality of repetition values being less than therepetition threshold. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the repetition threshold and the one of the one ormore of the plurality of repetition values, not to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine not to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of the oneor more of the plurality of repetition values being greater than therepetition threshold. The Rx wireless device (e.g., Rx UE2) may detectthe transport block scheduled by the SCI. Base on the detecting thetransport block, the Rx wireless device (e.g., Rx UE2) may transmit thepositive/negative acknowledgment to the Tx wireless device (e.g., TxUE1) in response to the Rx wireless device (e.g., Rx UE2) determining totransmit the positive/negative acknowledgment for the transport block.Each of the plurality of repetition values of the PSSCH may indicate aplurality of repetition transmissions of the PSSCH. The plurality ofrepetition transmissions may comprise transmission and retransmissionsof the PSSCH. In an example, the transmission and retransmissions of thePSSCH may comprise transmission and retransmissions of the PSSCH with asame or different redundancy versions of channel coding. The Tx wirelessdevice (e.g., Tx UE1) may transmit the PSCCH comprising the SCI to theRx wireless device (e.g., Rx UE2). The SCI may indicate the same ordifferent redundancy versions of channel coding for the plurality ofrepetition transmissions. The Rx wireless device (e.g., Rx UE2) mayreceive the PSCCH comprising the SCI via a reception resource pool. Thereception resource pool may comprise continuous or noncontinuousresources in frequency domain. The reception resource pool may comprisecontinuous or noncontinuous resources in time domain. The receptionresource pool may comprise a reception periodicity in sidelink. The Rxwireless device may receive the reception resource pool according to thereception periodicity in sidelink. In an example, the base station mayconfigure the reception periodicity of the reception resource pool tothe Rx wireless device (e.g., Rx UE2). In an example, the Tx wirelessdevice (e.g., Tx UE1) may configure the reception periodicity of thereception resource pool to the Rx wireless device (e.g., Rx UE2). The Rxwireless device (e.g., Rx UE2) may enhance/result in high reliabilityfor HARQ feedback and/or enable HARQ feedback with reduced signalingoverhead for the sidelink communication system.

FIG. 23 illustrates an example of a MAC CE structure. A Tx wirelessdevice (e.g., Tx UE1) may transmit the MAC CE to an Rx wireless device(e.g., Rx UE2) for activation/deactivation of one or more of theplurality of repetition values of the PSSCH. The MAC CE may comprise oneor more octets. The MAC CE may comprise a serving cell ID indication.The MAC CE may comprise a BWP ID indication. The Rx wireless device mayactivate/deactivate, based on the MAC CE, the one or more repetitionvalues of the Rx wireless device with the serving cell ID. The wirelessdevice may activate/deactivate, based on the MAC CE, the one or morerepetition values on a BWP with the BWP ID. The Rx wireless device mayactivate/deactivate, based on the MAC CE, the one or more repetitionvalues on a BWP of a cell with the BWP ID and the serving cell ID. In anexample, one bit of the MAC CE may be associated with one of theplurality of repetition values of the PSSCH configured by the RRCmessage (e.g., bi may be associated with one of the plurality ofrepetition values of the PSSCH, and i is from 0 to 15). In an example, abi may indicate an activated/deactivated status of one of the pluralityof repetition values of the PSSCH. In an example, when bi is set to “1”,a repetition value associated with bi may be activated. In an example,when bi is set to “0”, the repetition value associated with bi may bedeactivated. In an example, the MAC CE may be identified by a MAC PDUsub-header with an LCID. In an example, the LCID may be set to “101101”.

FIG. 24 illustrates an example of a procedure of groupcast (or unicast)transmission with repetition transmissions of V2V communication. A Txwireless device (e.g., Tx UE1) may receive one or more RRC messages froma base station at time T1. The one or more RRC messages may compriseconfiguration parameters. The configuration parameters may indicate: aplurality of repetition values of a PSSCH, and a repetition thresholdfor the PSSCH. Each of the plurality of repetition values of the PSSCHmay indicate a number of PSSCH repetition transmissions for a transportblock of the sidelink communication. The repetition threshold may be arepetition value for a transmission of a transport block. A Tx wirelessdevice and/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. The Rx wirelessdevice (e.g., Rx UE2) may receive one or more RRC messages from the Txwireless device (Tx UE1) at time T2. The one or more RRC messages maycomprise configuration parameters of sidelink communication. Theconfiguration parameters of sidelink communication may indicate: aplurality of repetition values of a PSSCH, and a repetition thresholdfor the PSSCH. Each of the plurality of repetition values of the PSSCHmay indicate a number of PSSCH repetition transmissions for a transportblock of the sidelink communication. The repetition threshold may be arepetition value for a transmission of a transport block. A Tx wirelessdevice and/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. In an example,the Rx wireless device (e.g., Rx UE2) may receive one or more RRCmessages from the base station at time T2. The one or more RRC messagesmay comprise configuration parameters of sidelink communication. Theconfiguration parameters of sidelink communication may indicate: aplurality of repetition values of a PSSCH, and a repetition thresholdfor the PSSCH. Each of the plurality of repetition values of the PSSCHmay indicate a number of PSSCH repetition transmissions for a transportblock of the sidelink communication. The repetition threshold may be arepetition value for a transmission of a transport block. A Tx wirelessdevice and/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. In an example,the configuration parameters may indicate a plurality of radio resourcesfor the Tx wireless device (e.g., Tx UE1). The plurality of radioresources may comprise one or more radio resource pools. The one or moreradio resource pools may comprise one or more transmission resourcespools. The one or more radio resource pools may comprise one or morereception resources pools. In an example, each resources pool of the oneor more transmission resource pools (or the one or more receptionresource pools) may comprise at least one of: a control region, and adata region. The Tx wireless device (e.g., Tx UE1) may transmit atransport block via the data region of a transmission resource poolaccording to control information in the control region of thetransmission resource pool. The Rx wireless device (e.g., Rx UE2) of theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6) may receive the transport block via the data regionof a reception resource pool of the Rx wireless device according tocontrol information in a control region of the reception resource pool.In an example, the transmission resource pool of the Tx wireless device(e.g., Tx UE1) may have an association relationship with the receptionresource pool of the Rx wireless device (e.g., Rx UE2). The associationrelationship may be a one-to-one mapping relationship. In an example,the configuration parameters may indicate the association relationshipto the Tx wireless device and/or the Rx wireless device (e.g., Tx UE1and/or Rx UE2).

The Rx wireless device (e.g., Rx UE2) may receive, from the Tx wirelessdevice (e.g., Tx UE1), a MAC CE activating one or more of the pluralityof repetition values of the PSSCH at time T3. The Rx wireless device(e.g., Rx UE2) may receive a PSCCH comprising a sidelink controlinformation (SCI) at time T4. The SCI may indicate one of the one ormore of the plurality of repetition values of the PSSCH. The SCI mayschedule a transport block with a number of repetition transmissions.The number of repetition transmissions may be the one of the one or moreof the plurality of repetition values of the PSSCH. The Rx wirelessdevice (e.g., Rx UE2) may determine, based on the repetition thresholdand the one of the one or more of the plurality of repetition values,whether to transmit a positive/negative acknowledgment for the transportblock scheduled by the SCI. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the repetition threshold and the one of the one ormore of the plurality of repetition values, to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI at time T5. In an example, the Rx wireless device (e.g., Rx UE2)may determine to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of the oneor more of the plurality of repetition values being equal to therepetition threshold. In an example, the Rx wireless device (e.g., RxUE2) may determine to transmit a positive/negative acknowledgment forthe transport block scheduled by the SCI in response to the one of theone or more of the plurality of repetition values being less than therepetition threshold. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the repetition threshold and the one of the one ormore of the plurality of repetition values, not to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine not to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of the oneor more of the plurality of repetition values being greater than therepetition threshold. The Rx wireless device (e.g., Rx UE2) may detectthe transport block scheduled by the SCI at time T6. The Rx wirelessdevice (e.g., Rx UE2) may transmit acknowledgement (ACK)/negativeacknowledgement (NACK) to the Tx wireless device (e.g., Tx UE1) inresponse to the Rx wireless device determining to transmit thepositive/negative acknowledgment at time T7.

FIG. 25 illustrates an example of a flow chart of groupcast (or unicast)transmission with repetition transmissions of V2V communication. An Rxwireless device (e.g., Rx UE2) may receive one or more RRC messages froma Tx wireless device (Tx UE1). The one or more RRC messages may compriseconfiguration parameters of sidelink communication. The configurationparameters of sidelink communication may indicate: a plurality ofrepetition values of a PSSCH, and a repetition threshold for the PSSCH.Each of the plurality of repetition values of the PSSCH may indicate anumber of PSSCH repetition transmissions for a transport block of thesidelink communication. The repetition threshold may be a repetitionvalue for a transmission of a transport block. A Tx wireless deviceand/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. In an example,the Rx wireless device (e.g., Rx UE2) may receive one or more RRCmessages from a base station. The one or more RRC messages may compriseconfiguration parameters of sidelink communication. The configurationparameters of sidelink communication may indicate: a plurality ofrepetition values of a PSSCH, and a repetition threshold for the PSSCH.Each of the plurality of repetition values of the PSSCH may indicate anumber of PSSCH repetition transmissions for a transport block of thesidelink communication. The repetition threshold may be a repetitionvalue for a transmission of a transport block. A Tx wireless deviceand/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. In an example,the configuration parameters may indicate a plurality of radio resourcesfor the Tx wireless device (e.g., Tx UE1). The plurality of radioresources may comprise one or more radio resource pools. The one or moreradio resource pools may comprise one or more transmission resourcespools. The one or more radio resource pools may comprise one or morereception resources pools. In an example, each resources pool of the oneor more transmission resource pools (or the one or more receptionresource pools) may comprise at least one of: a control region, and adata region. The Tx wireless device (e.g., Tx UE1) may transmit atransport block via the data region of a transmission resource poolaccording to control information in the control region of thetransmission resource pool. The Rx wireless device (e.g., Rx UE2) of theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6) may receive the transport block via the data regionof a reception resource pool of the Rx wireless device according tocontrol information in a control region of the reception resource pool.In an example, the transmission resource pool of the Tx wireless device(e.g., Tx UE1) may have an association relationship with the receptionresource pool of the Rx wireless device (e.g., Rx UE2). The associationrelationship may be a one-to-one mapping relationship. In an example,the configuration parameters may indicate the association relationshipto the Tx wireless device and/or the Rx wireless device (e.g., Tx UE1and/or Rx UE2).

The Rx wireless device (e.g., Rx UE2) may receive, from the Tx wirelessdevice (e.g., Tx UE1), a MAC CE activating one or more of the pluralityof repetition values of the. The Rx wireless device (e.g., Rx UE2) mayreceive a PSCCH comprising a sidelink control information (SCI). The SCImay indicate one of the one or more of the plurality of repetitionvalues of the PSSCH. The SCI may schedule a transport block with anumber of repetition transmissions. The number of repetitiontransmissions may be the one of the one or more of the plurality ofrepetition values of the PSSCH. The Rx wireless device (e.g., Rx UE2)may determine, based on the repetition threshold and the one of the oneor more of the plurality of repetition values, whether to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. The Rx wireless device (e.g., Rx UE2) may determine, based onthe repetition threshold and the one of the one or more of the pluralityof repetition values, to transmit a positive/negative acknowledgment forthe transport block scheduled by the SCI. In an example, the Rx wirelessdevice (e.g., Rx UE2) may determine to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI in responseto the one of the one or more of the plurality of repetition valuesbeing equal to the repetition threshold. In an example, the Rx wirelessdevice (e.g., Rx UE2) may determine to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI in responseto the one of the one or more of the plurality of repetition valuesbeing less than the repetition threshold. The Rx wireless device (e.g.,Rx UE2) may determine, based on the repetition threshold and the one ofthe one or more of the plurality of repetition values, not to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine not to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of the oneor more of the plurality of repetition values being greater than therepetition threshold. The Rx wireless device (e.g., Rx UE2) maydetect/receive the transport block scheduled by the SCI. The Rx wirelessdevice (e.g., Rx UE2) may transmit positive acknowledgement(ACK)/negative acknowledgement (NACK) to the Tx wireless device (e.g.,Tx UE1) in response to the Rx wireless device determining to transmitthe positive/negative acknowledgment.

A wireless device may receive one or more messages comprisingconfiguration parameters indicating: a plurality of repetition values ofa physical sidelink shared channel (PSSCH), and a repetition thresholdfor the PSSCH. The wireless device may receive a media access controlelement activating one or more of the plurality of repetition values.The wireless device may receive a sidelink control informationindicating one of the one or more of the plurality of repetition values.The wireless device may determine, based on the repetition threshold andthe one of the one or more of the plurality of repetition values, totransmit a positive/negative acknowledgment for a transport blockscheduled by the sidelink control information. The wireless device maydetect/receive the transport block scheduled by the sidelink controlinformation. The wireless device may transmit the positive/negativeacknowledgment in response to the determining. Each of the plurality ofrepetition values of the PSSCH may indicate a plurality of repetitiontransmissions of the PSSCH. The plurality of repetition transmissionsmay comprise transmission and retransmissions of the PSSCH. Thetransmission and retransmissions of the PSSCH may comprise transmissionand retransmissions of the PSSCH with different (or a same) redundancyversions. The different redundancy versions may be indicated to thewireless device via a sidelink control information. The differentredundancy versions may be indicated to the wireless device via aphysical downlink control channel. The repetition threshold for thePSSCH may be a repetition value for a transmission. The reception of thesidelink control information may comprise receiving the sidelink controlinformation from a reception resource pool. The reception resource poolmay comprise continuous or noncontinuous resources in frequency domain.The reception resource pool may comprise continuous or noncontinuousresources in time domain. The reception resource pool may comprise areception periodicity in a sidelink. The reception periodicity may beconfigured by a based station. The reception periodicity may beconfigured by a wireless device (e.g., a Tx wireless device). Thedetermination, based on the repetition threshold and the one of the oneor more of the plurality of repetition values, of transmitting thepositive/negative acknowledgment may comprise determining to transmitthe positive/negative acknowledgment in response to the one of the oneor more of the plurality of repetition values being less than therepetition threshold. The determination, based on the repetitionthreshold and the one of the one or more of the plurality of repetitionvalues, of transmitting the positive/negative acknowledgment maycomprise determining to transmit the positive/negative acknowledgment inresponse to the one of the one or more of the plurality of repetitionvalues being equal to the repetition threshold. The wireless device maydetermine not to transmit the positive/negative acknowledgment inresponse to the one of the one or more of the plurality of repetitionvalues being greater than the repetition threshold. The detection of thetransport block scheduled by the sidelink control information maycomprise detecting the transport block transmitted via a sidelink. Thereception of the one or more messages may comprise receiving, by thewireless device, the one or more messages from a first wireless device(e.g., a Tx wireless device). The first wireless device may performsidelink communication with the wireless device. The reception of theone or more messages may comprise receiving, by the wireless device, theone or more messages from a base station. The base station may comprisea coverage covering at least one of the first wireless device and thewireless device.

FIG. 26 illustrates an example of groupcast (or unicast) transmissionwith repetition transmissions of V2V communication. A Tx wireless device(e.g., Tx UE1) may communicate with a plurality of Rx wireless devices(e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) with agroupcast communication for a sidelink communication. The Tx wirelessdevice (e.g., Tx UE1) and the plurality of Rx wireless devices (e.g., RxUE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may be in a coverage ofa base station. The base station may transmit one or more radio resourcecontrol (RRC) messages to the Tx wireless device (e.g., Tx UE1). The oneor more RRC messages may comprise configuration parameters for the V2Vcommunication. The configuration parameters may indicate: a plurality ofrepetition values of a physical sidelink shared channel (PSSCH), and aplurality of repetition thresholds for the PSSCH. Each of the pluralityof repetition values of the PSSCH may indicate a number of PSSCHrepetition transmissions for a transport block of the sidelinkcommunication. Each of the plurality of repetition thresholds may be arepetition value for a transmission of a transport block. A Tx wirelessdevice and/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. In an example,the Tx wireless device (e.g., Tx UE1) may transmit a message to the basestation to request radio resources for the sidelink communication. In anexample, the message may be an RRC message. In an example, the messagemay comprise frequency information of transmitting and/or receivingsidelink data interested in by the Tx wireless device (e.g., Tx UE1).The configuration parameters may indicate a plurality of radio resourcesfor the Tx wireless device (e.g., Tx UE1). The plurality of radioresources may comprise one or more radio resource pools. The one or moreradio resource pools may comprise one or more transmission resourcespools. The one or more radio resource pools may comprise one or morereception resources pools. In an example, each resources pool of the oneor more transmission resource pools (or the one or more receptionresource pools) may comprise at least one of: a control region, and adata region. The Tx wireless device (e.g., Tx UE1) may transmit atransport block via the data region of a transmission resource poolaccording to control information in the control region of thetransmission resource pool. An Rx wireless device (e.g., Rx UE2) of theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6) may receive the transport block via the data regionof a reception resource pool of the Rx wireless device according tocontrol information in a control region of the reception resource pool.In an example, the transmission resource pool of the Tx wireless device(e.g., Tx UE1) may have an association relationship with the receptionresource pool of the Rx wireless device (e.g., Rx UE2). The associationrelationship may be a one-to-one mapping relationship. In an example,the configuration parameters may indicate the association relationshipto the Tx wireless device and/or the Rx wireless device (e.g., Tx UE1and/or Rx UE2).

The Tx wireless device (e.g., Tx UE1) may transmit one or more RRCmessages to an Rx wireless device of the plurality of Rx wirelessdevices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6). Inan example, the Tx wireless device (e.g., Tx UE1) may transmit the oneor more RRC messages to the Rx wireless device (e.g., Rx UE2) of theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6). The one or more RRC messages may compriseconfiguration parameters of sidelink communication. The configurationparameters of sidelink communication may indicate: a plurality ofrepetition values of a PSSCH, and a plurality of repetition thresholdsfor the PSSCH. Each of the plurality of repetition values of the PSSCHmay indicate a number of PSSCH repetition transmissions for a transportblock of the sidelink communication. Each of the plurality of repetitionthresholds may be a repetition value for a transmission of a transportblock. A Tx wireless device and/or a Rx wireless device maycontrol/determine whether a HARQ feedback is required based on therepetition threshold. The configuration parameters may indicate aplurality of radio resources for each of the plurality of Rx wirelessdevices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6). Inan example, the configuration parameters may indicate a plurality ofradio resources for the Rx wireless devices (e.g., Rx UE2). Theplurality of radio resources may comprise one or more radio resourcepools. The one or more radio resource pools may comprise one or moretransmission and/or reception resources pools. In an example, eachresources pool of the one or more transmission and/or reception resourcepools may comprise at least one of: a control region, and a data region.The Tx wireless device (e.g., Tx UE1) may transmit a transport block viathe data region of a transmission resource pool of the Tx wirelessdevice according to control information in a control region of thetransmission resource pool. An Rx wireless device (e.g., Rx UE2) of theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6) may detect the transport block via a data region ofa reception resource pool of the Rx wireless device according to controlinformation in a control region of the reception resource pool. Thecontrol information in the control region of the reception resource poolmay schedule the transport block of the data region of the receptionresource pool. In an example, the transmission resource pool of the Txwireless device (e.g., Tx UE1) may have an association relationship withthe reception resource pool of the Rx wireless device (e.g., Rx UE2). Inan example, the configuration parameters of sidelink communication mayindicate the association relationship to the Rx wireless device (e.g.,Rx UE2). In an example, the configuration parameters of sidelinkcommunication may indicate the association relationship between thetransmission resource pool of the Tx wireless device (e.g., Tx UE1) anda reception resource pool of an Rx wireless device of the plurality ofRx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, andRx UE6) to the Rx wireless device. In an example, the associationrelationship may be a one-to-one mapping relationship. The Rx wirelessdevice may detect the transport block transmitted by the Tx wirelessdevice according to the association relationship between thetransmission resource pool of the Tx wireless device (e.g., Tx UE1) andthe reception resource pool of the Rx wireless device (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, or Rx UE6).

In an example, the base station may transmit one or more RRC messages toan Rx wireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, orRx UE6) of the plurality of Rx wireless devices (e.g., Rx UE1, Rx UE2,Rx UE3, Rx UE4, Rx UE5, and Rx UE6). The one or more RRC messages maycomprise configuration parameters. The configuration parameters mayindicate: a plurality of repetition values of a PSSCH, and a pluralityof repetition thresholds for the PSSCH. Each of the plurality ofrepetition values of the PSSCH may indicate a number of PSSCH repetitiontransmissions for a transport block of the sidelink communication. Eachof the plurality of repetition thresholds may be a repetition value fora transmission of a transport block. A Tx wireless device and/or a Rxwireless device may control/determine whether a HARQ feedback isrequired based on the repetition threshold. In an example, the Txwireless device (e.g., Tx UE1) may transmit a message to the basestation to request radio resources for the sidelink communication. In anexample, the message may be an RRC message. In an example, the messagemay comprise frequency information of transmitting and/or receivingsidelink data interested in by the Tx wireless device. The configurationparameters may indicate a plurality of radio resources for the Rxwireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, or RxUE6). The plurality of radio resources may comprise one or more radioresource pools. The one or more radio resource pools may comprise one ormore transmission and/or reception resources pools. In an example, eachresources pool of the one or more transmission/reception resource poolsmay comprise at least one of: a control region, and a data region. TheRx wireless device (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, or RxUE6) may receive a transport block via the data region of a receptionresource pool according to control information in the control region ofthe reception resource pool. The Tx wireless device (e.g., Tx UE1) maytransmit the transport block via a data region of a transmissionresource pool of the Tx wireless device according to control informationin a control region of the transmission resource pool. In an example,the data region may comprise a PSSCH. The control region may comprise aPSCCH. In an example, the data region may comprise a PSSCH. The controlregion may comprise a PSCCH. In an example, the transmission resourcepool of the Tx wireless device (e.g., Tx UE1) may have an associationrelationship with the reception resource pool of the Rx wireless device(e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, or Rx UE6). In anexample, the configuration parameters may indicate the associationrelationship to the Tx wireless device (e.g., Tx UE1) and/or Rx wirelessdevice (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4, Rx UE5, or Rx UE6).

The Tx wireless device (e.g., Tx UE1) may transmit a transport block,via a PSSCH, to the plurality of Rx wireless devices (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) in a groupcast communication.The Tx wireless device (e.g., Tx UE1) may transmit the transport blockwith a number of repetition transmissions to the plurality of Rxwireless devices in a groupcast communication. The Tx wireless device(e.g., Tx UE1) may transmit a media access control control element (MACCE) indicating one of the plurality of repetition thresholds for thePSSCH to each of the plurality of Rx wireless devices. The Tx wirelessdevice (e.g., Tx UE1) may transmit a physical sidelink control channel(PSCCH) comprising a sidelink control information (SCI) scheduling thetransport block to the plurality of Rx wireless devices (e.g., Rx UE1,Rx UE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6). The SCI may indicate thenumber of the repetition transmissions. In an example, the number of therepetition transmissions may be one of the plurality of repetitionvalues of the PSSCH (e.g., indicated by the one or more RRC messages).The number of the repetition transmissions may comprise transmission andretransmissions of the transport block. A Rx wireless device (e.g., RxUE2) may receive, from the Tx wireless device (e.g., Tx UE1), the SCIindicating one of the plurality of repetition values of the PSSCH (e.g.,indicated by the one or more RRC messages). The Rx wireless device(e.g., Rx UE2) may determine, based on the one of the plurality ofrepetition thresholds and the one of the plurality of repetition values,whether to transmit a positive/negative acknowledgment for the transportblock scheduled by the SCI. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the one of the plurality of repetition thresholdsand the one of the plurality of repetition values, to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of theplurality of repetition values being equal to the one of the pluralityof repetition thresholds. In an example, the Rx wireless device (e.g.,Rx UE2) may determine to transmit a positive/negative acknowledgment forthe transport block scheduled by the SCI in response to the one of theplurality of repetition values being less than the one of the pluralityof repetition thresholds. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the one of the plurality of repetition thresholdsand the one of the plurality of repetition values, not to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine not to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of theplurality of repetition values being greater than the one of theplurality of repetition thresholds. The Rx wireless device (e.g., RxUE2) may detect the transport block scheduled by the SCI. Base on thedetecting the transport block, the Rx wireless device (e.g., Rx UE2) maytransmit the positive/negative acknowledgment to the Tx wireless device(e.g., Tx UE1) in response to the Rx wireless device determining totransmit the positive/negative acknowledgment for the transport block.The Rx wireless device (e.g., Rx UE2) may transmit the positive/negativeacknowledgment (e.g., ACK or NACK) to the Tx wireless device (e.g., TxUE1) via a physical sidelink feedback channel (PSFCH) in response to theRx wireless device determining to transmit the positive/negativeacknowledgment for the transport block. The PSFCH may comprise anassociation with the PSSCH used to transmit the transport block of theTx wireless device (e.g., Tx UE1). The configuration parameters mayindicate the association between the PSSCH and the PSFCH. The Rxwireless device (e.g., Rx UE2) may determine, based on the association,the PSFCH in response to receiving the PSSCH. In an example, the PSFCHmay use the same frequency resources as the PSSCH. In an example, thePSFCH may use a portion of frequency resources of the PSSCH. In anexample, the PSFCH may use frequency resources without overlapping withthe PSSCH. In an example, the Rx wireless device (e.g., Rx UE2) maytransmit a transport block via the PSFCH in response to the Rx wirelessdevice determining not to transmit the positive/negative acknowledgmentfor the transport block. Each of the plurality of repetition values ofthe PSSCH may indicate a plurality of repetition transmissions of thePSSCH. The plurality of repetition transmissions may comprisetransmission and retransmissions of the PSSCH. In an example, thetransmission and retransmissions of the PSSCH may comprise transmissionand retransmissions of the PSSCH with a same or different redundancyversions of channel coding. The Tx wireless device (e.g., Tx UE1) maytransmit the PSCCH comprising the SCI to the Rx wireless device (e.g.,Rx UE2). The SCI may indicate the same or different redundancy versionsof channel coding for the plurality of repetition transmissions. The Rxwireless device (e.g., Rx UE2) may receive the PSCCH comprising the SCIvia a reception resource pool. The reception resource pool may comprisecontinuous or noncontinuous resources in frequency domain. The receptionresource pool may comprise continuous or noncontinuous resources in timedomain. The reception resource pool may comprise a reception periodicityin sidelink. The Rx wireless device may receive the reception resourcepool according to the reception periodicity in sidelink. In an example,the base station may configure the reception periodicity of thereception resource pool to the Rx wireless device (e.g., Rx UE2). In anexample, the Tx wireless device (e.g., Tx UE1) may configure thereception periodicity of the reception resource pool to the Rx wirelessdevice (e.g., Rx UE2).

In an example, the Tx wireless device (e.g., Tx UE1) may transmit atransport block, via a PSSCH, to an Rx wireless device (e.g., Rx UE2) ina unicast communication. The Tx wireless device (e.g., Tx UE1) maytransmit a MAC CE indicating one of the plurality of repetitionthresholds for the PSSCH to the Rx wireless device (e.g., Rx UE2). TheTx wireless device (e.g., Tx UE1) may transmit the transport block witha number of repetition transmissions to the Rx wireless device (e.g., RxUE2). The Tx wireless device (e.g., Tx UE1) may transmit a PSCCHcomprising an SCI scheduling the transport block to the Rx wirelessdevices (e.g., Rx UE2). The SCI may indicate the number of therepetition transmissions. In an example, the number of the repetitiontransmissions may be one of the plurality of repetition values of thePSSCH (e.g., indicated by the one or more RRC messages). The number ofthe repetition transmissions may comprise transmission andretransmissions of the transport block. The Rx wireless device (e.g., RxUE2) may receive, from the Tx wireless device (e.g., Tx UE1), the SCIindicating one of the plurality of repetition values of the PSSCH. TheRx wireless device (e.g., Rx UE2) may determine, based on the one of theplurality of repetition thresholds and the one of the plurality ofrepetition values, whether to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI. The Rxwireless device (e.g., Rx UE2) may determine, based on the one of theplurality of repetition thresholds and the one of the plurality ofrepetition values, to transmit a positive/negative acknowledgment forthe transport block scheduled by the SCI. In an example, the Rx wirelessdevice (e.g., Rx UE2) may determine to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI in responseto the one of the plurality of repetition values being equal to the oneof the plurality of repetition thresholds. In an example, the Rxwireless device (e.g., Rx UE2) may determine to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI in response to the one of the plurality of repetition valuesbeing less than the one of the plurality of repetition thresholds. TheRx wireless device (e.g., Rx UE2) may determine, based on the one of theplurality of repetition thresholds and the one of the plurality ofrepetition values, not to transmit a positive/negative acknowledgmentfor the transport block scheduled by the SCI. In an example, the Rxwireless device (e.g., Rx UE2) may determine not to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI in response to the one of the plurality of repetition valuesbeing greater than the one of the plurality of repetition thresholds.The Rx wireless device (e.g., Rx UE2) may detect the transport blockscheduled by the SCI. Base on the detecting the transport block, the Rxwireless device (e.g., Rx UE2) may transmit the positive/negativeacknowledgment to the Tx wireless device (e.g., Tx UE1) in response tothe Rx wireless device (e.g., Rx UE2) determining to transmit thepositive/negative acknowledgment for the transport block. Each of theplurality of repetition values of the PSSCH may indicate a plurality ofrepetition transmissions of the PSSCH. The plurality of repetitiontransmissions may comprise transmission and retransmissions of thePSSCH. In an example, the transmission and retransmissions of the PSSCHmay comprise transmission and retransmissions of the PSSCH with a sameor different redundancy versions of channel coding. The Tx wirelessdevice (e.g., Tx UE1) may transmit the PSCCH comprising the SCI to theRx wireless device (e.g., Rx UE2). The SCI may indicate the same ordifferent redundancy versions of channel coding for the plurality ofrepetition transmissions. The Rx wireless device (e.g., Rx UE2) mayreceive the PSCCH comprising the SCI via a reception resource pool. Thereception resource pool may comprise continuous or noncontinuousresources in frequency domain. The reception resource pool may comprisecontinuous or noncontinuous resources in time domain. The receptionresource pool may comprise a reception periodicity in sidelink. The Rxwireless device may receive the reception resource pool according to thereception periodicity in sidelink. In an example, the base station mayconfigure the reception periodicity of the reception resource pool tothe Rx wireless device (e.g., Rx UE2). In an example, the Tx wirelessdevice (e.g., Tx UE1) may configure the reception periodicity of thereception resource pool to the Rx wireless device (e.g., Rx UE2). The Rxwireless device (e.g., Rx UE2) may enhance/result in high reliabilityfor HARQ feedback and/or enable HARQ feedback with reduced signalingoverhead for the sidelink communication system.

FIG. 23 illustrates an example of a MAC CE structure. A Tx wirelessdevice (e.g., Tx UE1) may transmit a MAC CE indicating one of theplurality of repetition thresholds for a PSSCH to an Rx wireless device(e.g., Rx UE2). The MAC CE may comprise one or more octets. The MAC CEmay comprise a serving cell ID indication. The MAC CE may comprise a BWPID indication. The Tx wireless device may indicate, via the MAC CE, theone of the plurality of repetition thresholds to the Rx wireless devicewith the serving cell ID. The Tx wireless device may indicate, via theMAC CE, the one of the plurality of repetition thresholds to the Rxwireless device with the BWP ID. The Tx wireless device may indicate,via the MAC CE, the one of the plurality of repetition thresholds to theRx wireless device on a BWP of a cell with the BWP ID and the servingcell ID. In an example, one bit of the MAC CE may be associated with oneof the plurality of repetition thresholds for the PSSCH configured by anRRC message (e.g., bi may be associated with one of the plurality ofrepetition thresholds for the PSSCH, and i is from 0 to 15). In anexample, a bi may indicate an activated/deactivated status of one of theplurality of repetition thresholds for the PSSCH. In an example, when biis set to “1”, a repetition threshold associated with bi may beindicated. In an example, when bi is set to “0”, the repetitionthreshold associated with bi may not be indicated. In an example, theMAC CE may be identified by a MAC PDU sub-header with an LCID. In anexample, the LCID may be set to “101101”.

FIG. 27 illustrates an example of a procedure of groupcast (or unicast)transmission with repetition transmissions of V2V communication. A Txwireless device (e.g., Tx UE1) may receive one or more RRC messages froma base station at time T1. The one or more RRC messages may compriseconfiguration parameters. The configuration parameters may indicate: aplurality of repetition values of a PSSCH, and a plurality of repetitionthresholds for the PSSCH. Each of the plurality of repetition values ofthe PSSCH may indicate a number of PSSCH repetition transmissions for atransport block of the sidelink communication. Each of the plurality ofrepetition thresholds may be a repetition value for a transmission of atransport block. A Tx wireless device and/or a Rx wireless device maycontrol/determine whether a HARQ feedback is required based on therepetition threshold. The Rx wireless device (e.g., Rx UE2) may receiveone or more RRC messages from the Tx wireless device (Tx UE1) at timeT2. The one or more RRC messages may comprise configuration parametersof sidelink communication. The configuration parameters of sidelinkcommunication may indicate: a plurality of repetition values of a PSSCH,and a plurality of repetition thresholds for the PSSCH. Each of theplurality of repetition values of the PSSCH may indicate a number ofPSSCH repetition transmissions for a transport block of the sidelinkcommunication. Each of the plurality of repetition thresholds may be arepetition value for a transmission of a transport block. A Tx wirelessdevice and/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. In an example,the Rx wireless device (e.g., Rx UE2) may receive one or more RRCmessages from the base station at time T2. The one or more RRC messagesmay comprise configuration parameters of sidelink communication. Theconfiguration parameters of sidelink communication may indicate: aplurality of repetition values of a PSSCH, and a plurality of repetitionthresholds for the PSSCH. Each of the plurality of repetition values ofthe PSSCH may indicate a number of PSSCH repetition transmissions for atransport block of the sidelink communication. Each of the plurality ofrepetition thresholds may be a repetition value for a transmission of atransport block. A Tx wireless device and/or a Rx wireless device maycontrol/determine whether a HARQ feedback is required based on therepetition threshold. In an example, the configuration parameters mayindicate a plurality of radio resources for the Tx wireless device(e.g., Tx UE1). The plurality of radio resources may comprise one ormore radio resource pools. The one or more radio resource pools maycomprise one or more transmission resources pools. The one or more radioresource pools may comprise one or more reception resources pools. In anexample, each resources pool of the one or more transmission resourcepools (or the one or more reception resource pools) may comprise atleast one of: a control region, and a data region. The Tx wirelessdevice (e.g., Tx UE1) may transmit a transport block via the data regionof a transmission resource pool according to control information in thecontrol region of the transmission resource pool. The Rx wireless device(e.g., Rx UE2) of the plurality of Rx wireless devices (e.g., Rx UE1, RxUE2, Rx UE3, Rx UE4, Rx UE5, and Rx UE6) may receive the transport blockvia the data region of a reception resource pool of the Rx wirelessdevice according to control information in a control region of thereception resource pool. In an example, the transmission resource poolof the Tx wireless device (e.g., Tx UE1) may have an associationrelationship with the reception resource pool of the Rx wireless device(e.g., Rx UE2). The association relationship may be a one-to-one mappingrelationship. In an example, the configuration parameters may indicatethe association relationship to the Tx wireless device and/or the Rxwireless device (e.g., Tx UE1 and/or Rx UE2).

The Rx wireless device (e.g., Rx UE2) may receive, from the Tx wirelessdevice (e.g., Tx UE1), a MAC CE indicating one of the plurality ofrepetition thresholds for the PSSCH at time T3. The Rx wireless device(e.g., Rx UE2) may receive a PSCCH comprising a sidelink controlinformation (SCI) at time T4. The SCI may indicate one of the pluralityof repetition values of the PSSCH. The SCI may schedule a transportblock with a number of repetition transmissions. The number ofrepetition transmissions may be the one of the plurality of repetitionvalues of the PSSCH. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the one of the plurality of repetition thresholdsand the one of the plurality of repetition values, whether to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. The Rx wireless device (e.g., Rx UE2) may determine, based onthe one of the plurality of repetition thresholds and the one of theplurality of repetition values, to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI at time T5.In an example, the Rx wireless device (e.g., Rx UE2) may determine totransmit a positive/negative acknowledgment for the transport blockscheduled by the SCI in response to the one of the plurality ofrepetition values being equal to the one of the plurality of repetitionthresholds. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of theplurality of repetition values being less than the one of the pluralityof repetition thresholds. The Rx wireless device (e.g., Rx UE2) maydetermine, based on the one of the plurality of repetition thresholdsand the one of the plurality of repetition values, not to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI. In an example, the Rx wireless device (e.g., Rx UE2) maydetermine not to transmit a positive/negative acknowledgment for thetransport block scheduled by the SCI in response to the one of theplurality of repetition values being greater than the one of theplurality of repetition thresholds. The Rx wireless device (e.g., RxUE2) may detect the transport block scheduled by the SCI at time T6. TheRx wireless device (e.g., Rx UE2) may transmit acknowledgement(ACK)/negative acknowledgement (NACK) to the Tx wireless device (e.g.,Tx UE1) in response to the Rx wireless device determining to transmitthe positive/negative acknowledgment at time T7.

FIG. 28 illustrates an example of a flow chart of groupcast (or unicast)transmission with repetition transmissions of V2V communication. An Rxwireless device (e.g., Rx UE2) may receive one or more RRC messages froma Tx wireless device (Tx UE1). The one or more RRC messages may compriseconfiguration parameters of sidelink communication. The configurationparameters of sidelink communication may indicate: a plurality ofrepetition values of a PSSCH, and a plurality of repetition thresholdsfor the PSSCH. Each of the plurality of repetition values of the PSSCHmay indicate a number of PSSCH repetition transmissions for a transportblock of the sidelink communication. Each of the plurality of repetitionthresholds may be a repetition value for a transmission of a transportblock. A Tx wireless device and/or a Rx wireless device maycontrol/determine whether a HARQ feedback is required based on therepetition threshold. In an example, the Rx wireless device (e.g., RxUE2) may receive one or more RRC messages from the base station. The oneor more RRC messages may comprise configuration parameters of sidelinkcommunication. The configuration parameters of sidelink communicationmay indicate: a plurality of repetition values of a PSSCH, and aplurality of repetition thresholds for the PSSCH. Each of the pluralityof repetition values of the PSSCH may indicate a number of PSSCHrepetition transmissions for a transport block of the sidelinkcommunication. Each of the plurality of repetition thresholds may be arepetition value for a transmission of a transport block. A Tx wirelessdevice and/or a Rx wireless device may control/determine whether a HARQfeedback is required based on the repetition threshold. In an example,the configuration parameters may indicate a plurality of radio resourcesfor the Tx wireless device (e.g., Tx UE1). The plurality of radioresources may comprise one or more radio resource pools. The one or moreradio resource pools may comprise one or more transmission resourcespools. The one or more radio resource pools may comprise one or morereception resources pools. In an example, each resources pool of the oneor more transmission resource pools (or the one or more receptionresource pools) may comprise at least one of: a control region, and adata region. The Tx wireless device (e.g., Tx UE1) may transmit atransport block via the data region of a transmission resource poolaccording to control information in the control region of thetransmission resource pool. The Rx wireless device (e.g., Rx UE2) of theplurality of Rx wireless devices (e.g., Rx UE1, Rx UE2, Rx UE3, Rx UE4,Rx UE5, and Rx UE6) may receive the transport block via the data regionof a reception resource pool of the Rx wireless device according tocontrol information in a control region of the reception resource pool.In an example, the transmission resource pool of the Tx wireless device(e.g., Tx UE1) may have an association relationship with the receptionresource pool of the Rx wireless device (e.g., Rx UE2). The associationrelationship may be a one-to-one mapping relationship. In an example,the configuration parameters may indicate the association relationshipto the Tx wireless device and/or the Rx wireless device (e.g., Tx UE1and/or Rx UE2).

The Rx wireless device (e.g., Rx UE2) may receive, from the Tx wirelessdevice (e.g., Tx UE1), a MAC CE indicating one of the plurality ofrepetition thresholds for the PSSCH. The Rx wireless device (e.g., RxUE2) may receive a PSCCH comprising a sidelink control information(SCI). The SCI may indicate one of the plurality of repetition values ofthe PSSCH. The SCI may schedule a transport block with a number ofrepetition transmissions. The number of repetition transmissions may bethe one of the plurality of repetition values of the PSSCH. The Rxwireless device (e.g., Rx UE2) may determine, based on the one of theplurality of repetition thresholds and the one of the plurality ofrepetition values, whether to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI. The Rxwireless device (e.g., Rx UE2) may determine, based on the one of theplurality of repetition thresholds and the one of the plurality ofrepetition values, to transmit a positive/negative acknowledgment forthe transport block scheduled by the SCI. In an example, the Rx wirelessdevice (e.g., Rx UE2) may determine to transmit a positive/negativeacknowledgment for the transport block scheduled by the SCI in responseto the one of the plurality of repetition values being equal to the oneof the plurality of repetition thresholds. In an example, the Rxwireless device (e.g., Rx UE2) may determine to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI in response to the one of the plurality of repetition valuesbeing less than the one of the plurality of repetition thresholds. TheRx wireless device (e.g., Rx UE2) may determine, based on the one of theplurality of repetition thresholds and the one of the plurality ofrepetition values, not to transmit a positive/negative acknowledgmentfor the transport block scheduled by the SCI. In an example, the Rxwireless device (e.g., Rx UE2) may determine not to transmit apositive/negative acknowledgment for the transport block scheduled bythe SCI in response to the one of the plurality of repetition valuesbeing greater than the one of the plurality of repetition thresholds.The Rx wireless device (e.g., Rx UE2) may detect the transport blockscheduled by the SCI. The Rx wireless device (e.g., Rx UE2) may transmitacknowledgement (ACK)/negative acknowledgement (NACK) to the Tx wirelessdevice (e.g., Tx UE1) in response to the Rx wireless device determiningto transmit the positive/negative acknowledgment.

A wireless device may receive one or more messages comprisingconfiguration parameters indicating: a plurality of repetition values ofa physical sidelink shared channel (PSSCH), and a plurality ofrepetition thresholds for the PSSCH. The wireless device may receive amedia access control control element indicating one of the plurality ofrepetition thresholds. The wireless device may receive a sidelinkcontrol information indicating one of the plurality of repetitionvalues. The wireless device may determine, based on the one of theplurality of repetition thresholds and the one of the plurality ofrepetition values, to transmit a positive/negative acknowledgment for atransport block scheduled by the sidelink control information. Thewireless device may detect/receive the transport block scheduled by thesidelink control information. The wireless device may transmit thepositive/negative acknowledgment in response to the determining. Each ofthe plurality of repetition values of the PSSCH may indicate a pluralityof repetition transmissions of the PSSCH. The plurality of repetitiontransmissions may comprise transmission and retransmissions of thePSSCH. The transmission and retransmissions of the PSSCH may comprisetransmission and retransmissions of the PSSCH with different (or a same)redundancy versions. The different redundancy versions may be indicatedto the wireless device via a sidelink control information. The differentredundancy versions may be indicated to the wireless device via aphysical downlink control channel. The repetition threshold for thePSSCH may be a repetition value for a transmission. The receiving thesidelink control information may comprise receiving the sidelink controlinformation from a reception resource pool. The reception resource poolmay comprise continuous or noncontinuous resources in frequency domain.The reception resource pool may comprise continuous or noncontinuousresources in time domain. The reception resource pool may comprise areception periodicity in a sidelink. The reception periodicity may beconfigured by a based station. The reception periodicity may beconfigured by a wireless device (e.g., a Tx wireless device). Thedetermination, based on the one of the plurality of repetitionthresholds and the one of the plurality of repetition values, oftransmitting the positive/negative acknowledgment may comprisedetermining to transmit the positive/negative acknowledgment in responseto the one of the plurality of repetition values being less than the oneof the plurality of repetition thresholds. The determination, based onthe one of the plurality of repetition thresholds and the one of theplurality of repetition values, of transmitting the positive/negativeacknowledgment may comprise determining to transmit thepositive/negative acknowledgment in response to the one of the pluralityof repetition values being equal to the one of the plurality ofrepetition thresholds. The wireless device may determine not to transmitthe positive/negative acknowledgment in response to the one of theplurality of repetition values being greater than the one of theplurality of repetition thresholds. The detection of the transport blockscheduled by the sidelink control information may comprise detecting thetransport block transmitted via a sidelink. The reception of the one ormore messages may comprise receiving, by the wireless device, the one ormore messages from a first wireless device (e.g., a Tx wireless device).The first wireless device may perform sidelink communication with thewireless device. The reception of the one or more messages may comprisereceiving, by the wireless device, the one or more messages from a basestation. The base station may comprise a coverage covering at least oneof the first wireless device and the wireless device.

A wireless device may receive one or more messages comprisingconfiguration parameters indicating: a plurality of repetition values ofa physical sidelink shared channel (PSSCH), and a plurality ofrepetition thresholds for the PSSCH. The wireless device may receive asidelink control information indicating one of the plurality ofrepetition values and one of the plurality of repetition thresholds. Thewireless device may determine, based on the one of the plurality ofrepetition values and the one of the plurality of repetition thresholds,to transmit a positive/negative acknowledgment for a transport blockscheduled by the sidelink control information. The wireless device maydetect/receive the transport block scheduled by the sidelink controlinformation. The wireless device may transmit the positive/negativeacknowledgment in response to the determining.

According to various embodiments, a device such as, for example, awireless device, off-network wireless device, a base station, and/or thelike, may comprise one or more processors and memory. The memory maystore instructions that, when executed by the one or more processors,cause the device to perform a series of actions. Embodiments of exampleactions are illustrated in the accompanying figures and specification.Features from various embodiments may be combined to create yet furtherembodiments.

FIG. 29 is a flow diagram as per an aspect of an example embodiment ofthe present disclosure. At 2910, a wireless device may receive one ormore messages. The one or more messages may indicate a plurality ofrepetition values of a physical sidelink shared channel (PSSCH). The oneor more messages may indicate a repetition threshold for the PSSCH. At2920, the wireless device may receive a sidelink control information(SCI). The SCI may schedule a transport block (TB). The SCI may indicatea first repetition value of the plurality of repetition values. At 2930,the wireless device may receive the transport block (TB) via the PSSCH.At 2940, the wireless device may determine, based on the firstrepetition value, to transmit an acknowledgment for the transport block(TB). The wireless device may determine, based on the repetitionthreshold, to transmit the acknowledgment for the transport block (TB).At 2950, the wireless device may transmit the acknowledgment for thetransport block (TB).

FIG. 30 is a flow diagram as per an aspect of an example embodiment ofthe present disclosure. At 3010, a wireless device may transmit asidelink control information (SCI). The SCI may schedule a transportblock (TB). The SCI may indicate a first repetition value of a pluralityof repetition values of a physical sidelink shared channel (PSSCH). At3020, the wireless device may transmit the transport block (TB) via thePSSCH. At 3030, the wireless device may receive an acknowledgment forthe transport block (TB).

According to various embodiments, a wireless device may receive one ormore messages. The one or more messages may indicate a plurality ofrepetition values of a physical sidelink shared channel (PSSCH). The oneor more messages may indicate a repetition threshold for the PSSCH. Thewireless device may receive a sidelink control information (SCI). TheSCI may schedule a transport block (TB). The SCI may indicate a firstrepetition value of the plurality of repetition values. The wirelessdevice may receive the transport block (TB) via the PSSCH. The wirelessdevice may determine, based on the first repetition value, to transmitan acknowledgment for the transport block (TB). The wireless device maydetermine, based on the repetition threshold, to transmit theacknowledgment for the transport block (TB). The wireless device maytransmit the acknowledgment for the transport block (TB).

According to various embodiments, the determination based on the firstrepetition value and the repetition threshold may be based on the firstrepetition value being equal to or less than the repetition threshold.According to various embodiments, each of the plurality of repetitionvalues of the PSSCH may indicate a plurality of repetition transmissionsof the PSSCH. According to various embodiments, the plurality ofrepetition transmissions of the PSSCH may comprise transmission andretransmissions of the PSSCH with different redundancy versions.According to various embodiments, the different redundancy versions maybe indicated to the wireless device via the sidelink controlinformation. According to various embodiments, the repetition thresholdfor the PSSCH may comprise a repetition value for a transmission.According to various embodiments, the reception of the sidelink controlinformation (SCI) comprises receiving the sidelink control information(SCI) from a reception resource pool. According to various embodiments,the transport block may be transmitted via a sidelink. According tovarious embodiments, the reception of the one or more messages maycomprise receiving, by the wireless device, the one or more messagesfrom a second wireless device. According to various embodiments, thereception of the one or more messages may comprise receiving, by thewireless device, the one or more messages from a base station.

According to various embodiments, a base station may transmit, to awireless device, one or more messages. The one or more messages mayindicate a plurality of repetition values of a physical sidelink sharedchannel (PSSCH). The one or more messages may indicate a repetitionthreshold for the PSSCH. According to various embodiments, a wirelessdevice may transmit a sidelink control information (SCI). The SCI mayschedule a transport block (TB). The SCI may indicate a first repetitionvalue of a plurality of repetition values of a physical sidelink sharedchannel (PSSCH). The wireless device may transmit the transport block(TB) via the PSSCH. The wireless device may receive an acknowledgmentfor the transport block (TB).

According to various embodiments, a wireless device may receive one ormore messages. The one or more messages may indicate a plurality ofrepetition values of a physical sidelink shared channel (PSSCH). The oneor more messages may indicate a repetition threshold for the PSSCH. Thewireless device may receive a media access control control elementactivating one or more repetition values of the plurality of repetitionvalues. The wireless device may receive a sidelink control information(SCI). The SCI may schedule a transport block (TB). The SCI may indicatea first repetition value of the one or more repetition values. Thewireless device may receive the transport block (TB) via the PSSCH. Thewireless device may determine, based on the first repetition value beingequal to or less than the repetition threshold, to transmit anacknowledgment for the transport block (TB). The wireless device maytransmit the acknowledgment for the transport block (TB).

According to various embodiments, a base station may transmit, to awireless device, one or more messages. The one or more messages mayindicate a plurality of repetition values of a physical sidelink sharedchannel (PSSCH). The one or more messages may indicate a repetitionthreshold for the PSSCH. According to various embodiments, a wirelessdevice may transmit a media access control control element activatingone or more repetition values of the plurality of repetition values. Thewireless device transmit a sidelink control information (SCI). The SCImay schedule a transport block (TB). The SCI may indicate a firstrepetition value of the one or more repetition values. The wirelessdevice may transmit the transport block (TB) via the PSSCH. The wirelessdevice may receive an acknowledgment for the transport block (TB).

According to various embodiments, a wireless device may receive one ormore messages. The one or more messages may indicate a plurality ofrepetition values of a physical sidelink shared channel (PSSCH). The oneor more messages may indicate a plurality of repetition thresholds forthe PSSCH. The wireless device may receive a media access controlcontrol element indicating a first repetition threshold of the pluralityof repetition thresholds. The wireless device may receive a sidelinkcontrol information (SCI). The SCI may schedule a transport block (TB).The SCI may indicate a first repetition value of the plurality ofrepetition values. The wireless device may receive the transport block(TB) via the PSSCH. The wireless device may determine, based on thefirst repetition value being equal to or less than the repetitionthreshold, to transmit an acknowledgment for the transport block (TB).The wireless device may transmit the acknowledgment for the transportblock (TB).

According to various embodiments, a base station may transmit, to awireless device, one or more messages. The one or more messages mayindicate a plurality of repetition values of a physical sidelink sharedchannel (PSSCH). The one or more messages may indicate a plurality ofrepetition thresholds for the PSSCH. According to various embodiments, awireless device may transmit a media access control control elementindicating a first repetition threshold of the plurality of repetitionthresholds. The wireless device transmit a sidelink control information(SCI). The SCI may schedule a transport block (TB). The SCI may indicatea first repetition value of the plurality of repetition values of thePSSCH. The wireless device may transmit the transport block (TB) via thePSSCH. The wireless device may receive an acknowledgment for thetransport block (TB).

According to various embodiments, a wireless device may receive one ormore messages. The one or more messages may indicate a plurality ofrepetition values of a physical sidelink shared channel (PSSCH). The oneor more messages may indicate a plurality of repetition thresholds forthe PSSCH. The wireless device may receive a sidelink controlinformation (SCI). The SCI may schedule a transport block (TB). The SCImay indicate a first repetition value of the plurality of repetitionvalues. The SCI may indicate a first repetition threshold of theplurality of repetition thresholds. The wireless device may receive thetransport block (TB) via the PSSCH. The wireless device may determine,based on the first repetition value being equal to or less than thefirst repetition threshold, to transmit an acknowledgment for thetransport block (TB). The wireless device may transmit theacknowledgment for the transport block (TB).

According to various embodiments, a base station may transmit, to awireless device, one or more messages. The one or more messages mayindicate a plurality of repetition values of a physical sidelink sharedchannel (PSSCH). The one or more messages may indicate a plurality ofrepetition thresholds for the PSSCH. According to various embodiments, awireless device may transmit a sidelink control information (SCI). TheSCI may schedule a transport block (TB). The SCI may indicate a firstrepetition value of the plurality of repetition values of the PSSCH. TheSCI may indicate a first repetition threshold of the plurality ofrepetition thresholds for the PSSCH. The wireless device may transmitthe transport block (TB) via the PSSCH. The wireless device may receivean acknowledgment for the transport block (TB).

According to various embodiments, a wireless device may receive one ormore messages. The one or more messages may indicate one or more radioresource pools for a physical sidelink shared channel. The wirelessdevice may receive, via the one or more radio resource pools, atransport block scheduled by a sidelink control information (SCI). TheSCI may indicate a communication range. The SCI may indicate ageographical location of a second wireless device. The wireless devicemay determine, based on the communication range and the geographicallocation, to transmit an acknowledgment for the transport block (TB).The wireless device may transmit, via a physical sidelink feedbackchannel, the acknowledgment to the second wireless device.

According to various embodiments, a base station may transmit, to awireless device, one or more messages. The one or more messages mayindicate one or more radio resource pools for a physical sidelink sharedchannel (PSSCH). According to various embodiments, a wireless device maytransmit, via the one or more radio resource pools, a transport blockscheduled by a sidelink control information (SCI). The SCI may indicatea communication range. The SCI may indicate a geographical location ofthe wireless device. The wireless device may receive an acknowledgmentfor the transport block (TB) via the PSSCH.

What is claimed is:
 1. A method comprising: receiving, by a wirelessdevice, a sidelink control information (SCI): scheduling a transportblock; and indicating a first repetition value; receiving, via aphysical sidelink shared channel (PSSCH), the transport block;determining, based on a comparison of the first repetition valuereceived via the SCI and a repetition threshold, to transmit anacknowledgment for the received transport block; and transmitting theacknowledgment for the received transport block.
 2. The method of claim1, wherein the determining, based on the comparison of the firstrepetition value received via the SCI and the repetition threshold, isbased on the first repetition value being equal to or less than therepetition threshold.
 3. The method of claim 1, further comprising aplurality of repetition values, wherein each of the plurality ofrepetition values of the PSSCH indicates a plurality of repetitiontransmissions of the PSSCH.
 4. The method of claim 3, wherein theplurality of repetition values of the PSSCH comprise transmission andretransmissions of the PSSCH with different redundancy versions.
 5. Themethod of claim 4, wherein the different redundancy versions areindicated to the wireless device via the sidelink control information.6. The method of claim 1, wherein the repetition threshold for the PSSCHcomprises a repetition value for a transmission sent to the wirelessdevice.
 7. The method of claim 1, wherein the receiving the sidelinkcontrol information comprises receiving the sidelink control informationfrom a reception resource pool.
 8. The method of claim 1, wherein thetransport block is received via a sidelink.
 9. The method of claim 1,wherein the repetition threshold is received via one or more radioresource control (RRC) messages.
 10. The method of claim 9, wherein theone or more RRC messages are received from at least one of a basestation and a second wireless device.
 11. A wireless device comprising:one or more processors; and memory storing instructions that, whenexecuted by the one or more processors, cause the wireless device to:receive a sidelink control information (SCI): scheduling a transportblock; and indicating a first repetition value; receive, via a physicalsidelink shared channel (PSSCH), the transport block; determine, basedon a comparison of the first repetition value received via the SCI and arepetition threshold, to transmit an acknowledgment for the receivedtransport block; and transmit the acknowledgment for the receivedtransport block.
 12. The wireless device of claim 11, wherein thedetermination, based on the comparison of the first repetition valuereceived via the SCI and the repetition threshold, is based on the firstrepetition value being equal to or less than the repetition threshold.13. The wireless device of claim 11, further comprising a plurality ofrepetition values, wherein each of the plurality of repetition values ofthe PSSCH indicates a plurality of repetition transmissions of thePSSCH.
 14. The wireless device of claim 13, wherein the plurality ofrepetition values of the PSSCH comprise transmission and retransmissionsof the PSSCH with different redundancy versions.
 15. The wireless deviceof claim 14, wherein the different redundancy versions are indicated tothe wireless device via the sidelink control information.
 16. Thewireless device of claim 11, wherein the repetition threshold for thePSSCH comprises a repetition value for a transmission sent to thewireless device.
 17. The wireless device of claim 11, wherein receivingthe sidelink control information further comprises receiving thesidelink control information from a reception resource pool.
 18. Thewireless device of claim 11, wherein the transport block is received viaa sidelink.
 19. The wireless device of claim 11, wherein the repetitionthreshold is received via one or more radio resource control (RRC)messages.
 20. A system comprising: a first wireless device comprising:one or more first processors; and first memory storing firstinstructions that, when executed by the one or more first processors,cause the first wireless device to: transmit a sidelink controlinformation (SCI): scheduling a transport block; and indicating a firstrepetition value; transmit, via a physical sidelink shared channel(PSSCH), the transport block; and receive an acknowledgment for thetransport block; and a second wireless device comprising: one or moresecond processors; and second memory storing third instructions that,when executed by the one or more second processors, cause the secondwireless device to: receive the sidelink control information: receive,via the PSSCH, the transport block; determine, based on a comparison ofthe first repetition value received via the SCI and a repetitionthreshold, to transmit the acknowledgment for the received transportblock; and transmit the acknowledgment for the received transport block.